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For three-season backpacking in most of the continental United States, a 20-degree bag is an ideal choice. When it’s warm it can be used like a quilt, when a late season or high elevation trip has a cold night or two dropping into the teens it will be adequate if not downright comfortable (especially if paired with a down jacket and thick socks), and for nights where low temperatures range in the upper 20s to low 40s it seems perfect. Although I’ve owned 30-degree bags and 15-degree bags over the past decade, and used them from Appalachia to Arizona, I subsequently switched to a Feathered Friends Hummingbird UL 20 for most of my spring, summer, and fall backpacking trips in the broader Pacific Northwest region.

Cowboy camping with the Feathered Friends Hummingbird Sleeping Bag
The Feathered Friends Hummingbird UL 20
The Hummingbird UL 20, which keeps up with the avian-themed names for Feathered Friends sleeping bags, is an immediately impressive bag when tossed out to loft up. The efficient design and sharp, rich colors of the fabric are apparent even to the most novice backpacker. It just looks like a great sleeping bag.
I’ve used the bag directly under the stars – as well as in tents, bivy sacks, fire lookouts, and in the back of my Honda Element. It’s seen crisp, high desert nights in the low 20s and rainy, barely above freezing autumn nights in low elevation canyons in Idaho. The bulk of its use has been in fairly typical “summer” backpacking conditions in the Northern Rockies and Cascades, with lows in the mid-30s to mid-40s and fairly dry conditions. All things considered, I’ve put this bag through a substantial amount of testing in its intended conditions.

One aspect of this bag that never ceases to astound me, and is crucial as far as making it a great sleeping bag for backpackers, is its remarkably light weight for the temperature rating. The regular is listed as 1 lb. 8 ounces, with 14 ounces of 950+ down fill. When weighed on a postal scale, the actual weight registered as 1 lb. 9.73 ounces. The down is not treated with any hydrophobic process. When removed from a Sea to Summit dry compression sack (it compressed to slightly larger than a volleyball) it lofts up rather quickly and the horizontal baffles consistently keep the down where it is needed even when tossing and turning at night. If less compression is needed but waterproofing still desired, packing the Hummingbird UL 20 in an Ultra-Sil dry bag would be another option.
As expected, a bag this light and warm doesn’t have a lot of “luxury” features. Over the years, I’ve found that most of these features are nice but not crucial and are perhaps a bit overhyped in the marketing for many mass-produced bags that you might find on the shelf at many retailers. There’s something to be said for not getting tangled up in a multitude of draw strings and cord locks when trying to adjust or exit a sleeping bag.
One of the more common features which is absent on this bag is a dedicated draft collar. An overstuffed baffle (“passive collar” per the Feathered Friends description) compensates for this nicely and it is only when the temperatures edges close to the 20 degree mark that I start wishing for a draft collar I could cinch down. I've been comfortable in this bag near the 20-degree rating on a sleeping pad with a 4.9 R-value and a down jacket draped over my chest inside the bag as an improvised draft collar. Even with its minimalist design, this is a bag that can reach down to the limits of its rating without much assistance. A down jacket can be arranged to imitate a draft collar and is fairly effective. On a brighter note, a well-designed and sufficiently stuffed draft tube is perfect at keeping cold air from sneaking in via the zipper.

The Pertex Endurance UL shell fabric (ultralight, 10 denier, water-resistant / breathable) is featherweight but durable enough to not induce anxiety. It breathes very well and even on warm nights. The lining, Flite 15 denier ripstop nylon, never felt unbearably clammy on my skin. I did notice that while the fabric never seemed to wet out, even when inside a bivy sack during a drizzle when impressive amounts of condensation formed, that overnight dew or other minor amounts of moisture didn’t tend to bead up the way they had on other bags in similar conditions. I’m not sure if this is a function of the fabric, the DWR treatment, or the conditions, but it was noticeable. Fortunately, it didn’t seem to impact the performance of the bag in the slightest.
Additionally, I found the shell to dry quickly when left to air out and in direct sunlight it seemed to dry almost instantaneously. If needed you could always boost and / or restore the DWR with a spray-on DWR treatment. A handy fabric loop on the bottom allows the bag to easily be hung if you feel compelled to really air it out. Feathered Friends also offers another version of the Hummingbird, the Hummingbird YF 20 which utilizes higher denier fabrics and is a few ounces heavier than the UL reviewed here, but also cheaper.

This bag has the slimmest cut of any bag I’ve owned, but it never felt claustrophobic to me. The shoulder girth is 58”, the hip girth is 52”, and the footbox girth is 38”. As someone who is 5’10” and on the slimmer side, I found the regular length (up to 6’) to be an excellent fit. I’ve usually found footboxes to be something I rarely notice unless it is a particularly awkward design, but the footbox on this bag stands out as one that is especially comfortable. Despite the slim cut, I found this bag to offer plenty of room and even when bringing in a down jacket on frigid nights and when using body heat to dry pair or two of socks, gloves, a hat, and maybe a shirt, it never felt crowded.

The zipper is on the left side of the bag and, as a two-way zipper, allows for ventilating from the footbox while still keeping the top of the bag zipped up. I wish I could leave discussion of the zipper at that, but unfortunately my experience with the zipper was the only disappointing factor of the entire bag. The snipper zags often unless a substantial amount of care and focus are applied to the task at hand. While this seems easy enough, when you wake up in the middle of the night and need to exit the bag with some degree of urgency, or are returning to the bag and eager to get yourself zipped back into its warm embrace, it becomes surprisingly difficult. Even when my brain isn‘t addled by sleep, I have found the zipper to be uncommonly easy to snag, which isn’t a desirable distinguishing feature. By no means does the zipper snag every time (and I have had sleeping bags where they did), but I found myself spending more time pulling fabric free of the zipper with this bag than I have with my Feathered Friends Snowbunting bag or the Marmot bags I have owned.

The Hummingbird UL 20 from Feathered Friends has proven to be suitable across a wide range of conditions.
Conclusion
At a price of $609, this bag is a serious investment for serious backpackers. However, it is without a doubt a bag that means business – incredibly and well-engineered. I would have a difficult time seeing someone regretting purchasing this bag after using it on a few trips. Feathered Friends construction quality is consistently impressive in my experience, is made in the United States, and I have few doubts that this bag will likely outlast pretty much every other piece of gear I own, aside from perhaps my titanium mug.
Aside from the slight zipper conundrum, which is frustrating but can be alleviated by a concentrated and deliberate effort at performing a basic task, this is an otherwise excellent bag. It is perhaps akin to getting a vehicle that is otherwise perfectly suited to your needs and in your favorite color, but the cup holder is just a bit too small for your favorite coffee mug.
The Hummingbird UL 20 retails for $609 – find it here at Feathered Friends.
Editor's Note: This review originally appeared in Issue 36 of TrailGroove Magazine. You can read the article here for additional photos, pros and cons, and our rating of the Hummingbird UL 20.

For groups of two looking for a lightweight backpacking tent with decent elbow room, the choice of lightweight backcountry shelters can at times seem limited. The category can be narrowed down to just a few contenders quite quickly, with one of the leading candidates being the topic of this review, the venerable Six Moon Designs Lunar Duo. A single-walled shelter offering 34 square feet of interior floor space, the Lunar Duo offers a nicely adequate floor plan for 2 or luxury for 1. This is a welcome change compared to many other “2 person” offerings on the market, most of which are really simply large 1 person tents and a tight, mostly unlivable squeeze for 2.

Not only does the Lunar Duo serve up more interior room than most competitors, it also includes 2 side entry doors and two huge vestibules at 12 square feet each. All of this at a space to weight ratio that few 2 person mainstream tents can match. Beginning back in 2012, the Lunar Duo is offered in both silnylon and polyester fabric versions. In this review we’ll discuss both models and feature our experiences with the predecessor to the lighter “Explorer” silnylon offering as well as the Explorer itself.
Lunar Duo Design
To save weight, the tent uses the two trekking poles that you’re hopefully already carrying for support (set to 45”). If you’re not a trekking pole user, Six Moon Designs (SMD) offers a carbon fiber pole (you’ll need 2) that can be purchased separately. Trekking pole user or not, every Lunar Duo comes with a pair of short, curved Easton aluminum spacer poles that are inserted into an interior sleeve sewn into the roof on each side of the tent during setup. An elastic pouch secures the poles in place and the result is a ceiling that peaks into a smooth curve rather than the sharp, angular roofline of many tents. As a result, headroom is greatly increased. A minimum of 6 stakes are required for setup. 6 additional tie-outs surround the tent – offering a greater amount of wind resistance if needed. Line tensioners are included for each of the 6 main stake points. Stakes are not included – SMD offers stakes for purchase separately for the tent or if you prefer, you can assemble your own set. This adds a silver lining to the potential drawback of the situation – you can assemble a package that best suits your needs with any of combination of stakes that you wish. We found that a setup of MSR Ground Hogs along with shepherd’s hook stakes work best for this tent.

There are two versions of the Lunar Duo, the lighter and more expensive Explorer Lunar Duo (30d silnylon) version ($395), and the 1 lb. heavier but cheaper $210 Outfitter version (190T Polyester). Either way, the canopy of the tent protects the occupants nicely from wind driven rain, overlapping the inner living space significantly on all sides. Dual zippered doors offer each person an easy entry and exit through the large vestibule on each side. Each vestibule secures to a hook that slides down the side guy line using a prussic knot. This allows the user to slide the vestibule up and down for more views and ventilation, or farther down for greater weather protection. If desired, you can also enter and exit the tent this way (by simply sliding the vestibule upwards), though you’ll have to duck a bit lower than if you fully unzip the vestibule to exit.
Once unzipped, SMD provides a loop and toggle system that allows you to roll each side of the vestibule up and secure it to the main tent body. This allows for the best views and ventilation in good weather, and the easiest entry and exit. In practice we found ourselves mostly deploying the vestibule at night and simply sliding it up the line and down to enter and exit. A peak vent on each side of the tent assists with ventilation. At first glance they look as though they might be penetrated by a driving rain, but in practice they functioned well. They are located in the vestibule section, so even in a worst case scenario the living quarters wouldn’t be affected.

A full enclosure of ultralight no-see-um netting completes the Lunar Duo’s design, resulting in complete protection from crawling and flying insects. A pocket is sewn into the netting on each side for storage of essential items. For the floor you’ll again find 30d silnylon in the Explorer and 190T Polyester for the Outfitter. The floor is shaped to create a bathtub design with generously sized sidewalls all around. At 54” wide by 90” long, the floor plan is quite generous as well. 45” of headroom allows even taller hikers to sit up comfortably – and since the roofline isn’t sloped side to side, this full height can be used by both occupants. 6 guyline points are included surrounding the tent for additional stability if desired, guylines not included.
The packed size is 15” by 6” with a 20” circumference. Seam-sealing is required – you can either opt to DIY with a tube of seam-sealer or SMD will take care of the process as a $35 option. One great thing about the design is that there are no seams to seal on the floor - and overhead you’ll find a seamless sheet of fabric as well until you reach the head and foot end of the tent where the insect netting is sewn in. Basically, while sealing is still required, it’s not quite as critical as other lightweight shelters where seams are running directly over your head and underneath your pad.
Unfortunately, while SMD expanded their Lunar Duo lineup in 2012 with the more affordable & 1 lb. heavier Outfitter model, we were also hoping they’d go the other way as well and release a lighter cuben fiber model to round out the lineup. SMD previously released the now discontinued Refuge X 2 person tent in cuben / Dyneema Composite Fiber, and recently they’ve begun to release solo models as well as 2 person tarps using the superlight but strong material. So far, no word on Dyneema Composite Fiber for the Lunar Duo, but we’re keeping our fingers crossed.

The Lunar Duo offers ample space for 2 hikers, plus a bit more especially when at least one shorter sleeping pad is used.
In Practice
Setup
The tent takes approximately 5-10 minutes to setup, and is about as easily done with 1 or 2 people. While the instructions call for spacer pole insertion prior to pitching the tent, this involves reaching into the living quarters to insert the poles. The tent has a lot of fabric, and we found at times it could be difficult to make sense of all that nylon while inserting the poles. Additionally, opening up the inside of your tent to the elements in rainy weather is obviously not ideal. We found that pitching the tent first and inserting the spacer poles later worked fine and was more convenient. The tent also works pretty well without the spacer poles, but you’ll lose headroom.
The spacer poles are made from Easton aluminum and weigh 2.6 oz. for the pair. We found that it was best to pitch with the vestibules closed – otherwise you might end up with a bad main guyline angle that won’t allow you to close the vestibules (easily fixed with a quick re-stake). Another tip is set the main guylines just slightly to the left of each vestibule zipper – this allows the silnylon flap that lays over the zipper for additional rain protection to lay flat. One complaint is that this flap snags easily on the zipper when the vestibule is not taut. However, due to the slippery nature of silnyon, it’s a pretty quick and easy fix.
Space & Livability
The tent is very spacious. Not only is there room for 2 full size inflatable sleeping pads, there is enough room to fit both in with extra space between the pads and again on each side. The floor is also quite long at 90 inches, so you’ll have quite a bit of additional room at the head and foot end as well. On top of all that, each vestibule has enough room to store a full pack out of the elements, yet still allow space for an easy entry and exit. The tent was quite large enough for the two of us plus our 50 lb. 4-legged hiking companion and our gear. The canopy significantly overlaps the interior on all sides – so even if you find the foot of your sleeping bag pressed up against the netting of the tent for example, you’re still well protected from rain and splash. While the footprint is large, we’ve used the Lunar Duo in everything from old growth forests to alpine environments and so far, we’ve never had an issue finding a spot to setup camp.

The Lunar Duo offers ample vestibule storage on 2 sides.
Support System
With this much space, we found that a taut pitch was needed for good stability in windy conditions. Trekking poles, due to their extreme stiffness and strength helped a lot in this regard – really allowing you to tighten things down while maintaining the roofline. We also tested the optional carbon fiber pole set that SMD offers for those who aren’t trekking pole users. At $80 per pair at 3.6 oz., the price is on the steep side but lighter than trekking poles. The poles worked in practice and I wouldn’t hesitate to use them for most trips. However, to really tighten up the tent so much downward force is exerted from top to bottom that the carbon poles begin to bow. This didn’t cause any problems and the poles never broke, but to some extent it was still disconcerting. Still, the poles held up great in 20-30mph winds and do an adequate job, but don’t quite inspire the same confidence as trekking poles. You can also opt for a pair of cheaper aluminum poles for $30 per pair at 6 oz.
Wind, Guylines, & Stakes
Trekking poles or not, we highly suggest using the optional tieouts to increase stability. The Lunar Duo offers a single tieout at both the foot and head end as well as a tieout on each side of both vestibules. For maximum wind resistance, all tieouts should be used but we found this to be overkill even in very windy alpine camps. In the interest of saving weight, we found the best method for dealing with wind was to pitch one vestibule into the wind, then utilize both tieouts on that (the windward) side only (less guylines and stakes). We used 5’ of 3 mm utility type cord for our extra guylines, combined with a lineloc type tensioner to make tensioning a little easier (the 5’ length is greatly reduced after it’s looped through a lineloc and tensioned). If you’d like to be able to easily switch between sides, you can attach these with a loop to loop connection or simply always pitch that side of the tent into the wind. Using micro linelocs and a thinner line could save some weight, though a loop connection probably wouldn’t be ideal (could be hard to remove after being under tension). Since our experience is with the silnylon version where sag is always a factor, we permanently attached tieouts of the same length and again with a lineloc to the head and foot end of the tent.

This helps a bit no matter which way the wind is blowing but also ensures that the tent stays off the foot of your sleeping bag (or head) if the tent begins to sag due to moisture in the middle of the night. How many of these tieouts to use definitely depends on personal preference and conditions. For maximum stability use them all, or none if you expect still & dry weather or don’t mind a bit of shiftiness when the wind picks up. I found the method above to be the best all-around balance and kept things stable enough in 45mph gusts, the highest we experienced in the Duo. If it’s a bit too drafty inside, you can even lower your trekking poles a bit and batten the shelter down all the way to the ground, but at the cost of ventilation and headroom. The extra tieouts do great with lightweight shepherd's hook stakes, though for the 4 corners and especially the two main guylines running under each vestibule a stake with better holding power like the MSR Ground Hog was preferred.
Rain & Humidity
The Lunar Duo offers great protection from rain – due to the overlapping canopy rainstorms are of little concern and with all that space and headroom, being tent-bound due to weather isn’t such a bad thing. Vertical sidewalls prevent rain from entering during entry and exit. One issue inherent to all silnylon shelter designs is sag – especially when wet and the Duo is no exception. After setup, we found that a quick re-tension of the guylines was required after an hour or so after the fabric had a chance to stretch. SMD makes it pretty easy however, with tensioners at each corner allowing you to cinch things up without having to re-stake and a lineloc for the side guylines that you can even re-tension from inside the tent. When setting up your tent, loosen each of these lines to allow for maximum tightening later, and if you’re using linelocs for your extra guylines this is quick work as well. Generally, this was sufficient to keep the Duo taut until the next morning, however if humid or rainy weather rolled in you’ll again be faced with the need to tighten things up – at which point the tent should maintain its pitch well until you’re ready for departure.

When we declined to venture out due to the weather in the middle of the night however, the tent never sagged so much that it became a huge problem, though some head & foot room would be compromised and wind resistance would also be affected. The polyester Outfitter model should have much less of an issue in this regard. Condensation inside the tent was also a concern, although always just a nuisance and only during humid weather. Whenever possible, sleep with the vestibules raised for maximum ventilation to counteract the issue. Both cases were combated with the occasional wipe down of the interior roof fabric using a pack towel and even at the worst, the DWR shell of our sleeping bags was enough to keep us warm and dry – although if you're experiencing a high condensation night, you’ll want to keep the shelter tight for clearance so you aren’t rubbing the foot of your sleeping bag against a damp ceiling as you sleep.
The Lunar Duo is a 3-season shelter but we ventured into snowy conditions on more than one occasion. While a light dusting of snow is of no concern, if more than an inch or so is expected to fall a shelter offering more snow load support would be recommended. The 30d sil floor of the tent does have the potential to leak under high pressure if you were for example, to kneel on the floor over wet ground. We always used a lightweight polycro groundsheet underneath (mostly to extend the life of the floor) and never had any issues with water seeping in from below. Even without a groundsheet, you should be fine as long as you’re not setup on extremely soggy ground and placing high pressures (knees, elbows, etc.) on specific parts of the floor.
Modifications
Floor
I decided to make a few very small modifications to our Lunar Duo. First and foremost was a seam-seal treatment for the floor that we think most everyone will find quite an asset. Stock, the floor is quite slippery and if you’re setup on any type of incline (which seems to be almost 100% of the time for spots I pick) you’ll soon find you and your sleeping pad slowly sliding downhill. Setting up the tent at home, a seam-sealer set of stripes, dots, or patterns of your choice across the inside of the floor will greatly help in this regard.
Vestibule Attachment
There are two webbing loops that SMD has attached to the end of each vestibule. Attaching these loops onto the hook attached to the main guylines allows you to slide the vestibules up or down and secure them tightly when needed for weather protection. We began to find this attachment process cumbersome – the loops are large and the opening of the hook small. Attaching the loops and removing them was tedious, especially when you were leaning out of the interior of the tent at night, trying to attach each loop to secure the vestibule for potential bad weather rolling in. The solution was to tie 4 lengths of 3 mm cord to the each webbing attachment point, essentially forming a new loop that is much easier to attach and detach when needed. With the hook under tension, there is no risk of an accidental disengagement.

Adding loops of cord to the vestibule attachment system greatly improved the vestibule securing process and disengagement.
Zipper Pulls & Corner Tieouts
No zipper pulls were included with our Lunar Duo. The addition of glow in the dark paracord pulls makes life just a bit easier in the darkness. We also elected to tie a double knot at the end of each corner tieout – forming a nice handle for quick one-handed re-tensioning.
Changes Compared to Older Lunar Duo Tents
Models
Starting in 2012 SMD streamlined the Lunar Duo line while adding a lower cost option made from Polyester fabric. The Explorer is now the silnylon Lunar Duo, and comes in at a pound lighter but $185 more than the Explorer. Offering a lower cost version of such a well-designed tent is a great idea especially where pack weight might not be the largest concern. Even at 57 oz. however, the Outfitter is still pretty light when you’re looking at the 2 person tent market as a whole.
Floor
Previously, the Lunar Duo had two floor options – an “Ultralight” as well as a “Standard” option. The ultralight option was made from 30d silnylon with the standard floor utilizing a 70d fabric with a 4 oz. weight difference between the two. For 2012 the 30d “Ultralight” became the standard and only option on the Explorer with the 70d floor eliminated from production. There were pros and cons to both options. We tested the ultralight option in our pre-2012 model. Our reasoning behind this was that even with a lightweight polycro groundsheet; this combo came out lighter than the standard floor with no groundsheet…and it’s easier to replace a cheap groundsheet than an entire tent floor. One benefit the standard floor had is that its tackiness was built in, so the anti-slide floor treatment we described earlier was more of an option than a necessity and the floor was waterproof to a greater degree than the 30d, now standard floor.
Zipper, Fabric, & Color
Gone these days is the classic bright green color option, with the Lunar Duo now made only in the more subtle grey or olive colors depending on availability it seems. Though we never had any issues with the zipper of the previous version, it’s now been beefed up to a sturdier #5 version, which does seem to result in a slightly smoother action as well. Corner tieouts and other various points around the tent have been more heavily reinforced and the silnylon has also been upgraded to a more premium & waterproof fabric on the Explorer version compared to the pre-2012 models. According to SMD, this new fabric is a substantial improvement and offers approximately twice the waterproofness / hydrostatic head rating compared to the previous models. In our opinion, this is a huge selling point. We only experienced slight misting (where the intense pressure of the rain is enough to result in an extremely fine mist through the fabric and into the tent) in the older Lunar Duo in the heaviest of rains – resulting in a small nuisance rather than a problem. The new fabric should make an already great shelter that much better. In our testing, the fabric did indeed offer a very significant increase in waterproofness compared to the older model.

Modified vestibule attachment system in use
Admittedly however, our older model has seen significantly more use. With these changes, the weight of 2012+ redesigned Lunar Duos went up to a listed weight of 41 oz. (currently up again to 45 oz.), where previously the tent was listed at 39 oz. with the 30d ultralight floor (all weights prior to seam-sealing). You’ll also find a small change in the way the arch poles secure into their sewn-in roof sleeves – instead of a Velcro closure, they now secure with an elastic & pouch arrangement. SMD has designed a flap of silnylon that overlaps the vestibule zipper when closed and taut. One new welcome addition for 2012 is an additional Velcro securement point halfway up the vestibule just to help keep the flap in place over the zipper and offer some additional rain protection for whatever you have stored underneath each vestibule for the night. After seam-sealing the new model, we did find a few more loose thread ends vs. the original model and the new reinforced corner tieouts exhibited some thread stress / cutting through the fabric on each corner after our first pitch. We seam-sealed these areas a bit more heavily and so far, so good. One final point was that while our doors were opposing on the older model, the doors are now in the same position side to side.
Specifications
Pre-2012 LD Weight After Seam-sealing & Anti-slip Floor Treatment with Spacer Poles in Stuff Sack: 40.5 oz. (No Stakes) 2012 LD Weight in Stuff Sack w/ Spacer Pole Prior to Sealing: 41.1 oz. (Listed Weight: 41 oz. – Current Listed Weight: 45 oz.) After Sealing in Stuff Sack with Spacer Poles: 43.4 oz. Carbon Fiber Poles: 3.6 oz. Aluminum Poles: 6 oz. 3 mm Guylines w/ Linelocs .3 oz. each Polycro Groundsheet: 2.8 oz.
Seam-sealed new Lunar Duo
Conclusion
Time after time the Lunar Duo has met our expectations, kept us dry, and kept our packs lighter compared to alternative traditional shelters offering this much space. The space to weight ratio is impressive and for groups of two it’s hard to compete with so much livability. Each person has their own door. Each person has their own vestibule capable of sheltering their gear from the elements. Inside, there’s still a lot of elbow room and you don’t have to draw straws to see who gets the short side – the high roof treats all occupants equally. Over time the shelter has been upgraded with a more waterproof fabric as well as had changes implemented to increase durability, increasing the overall weight slightly. We never had any issues with durability using the older version, so we have mixed feelings about the changes. On one hand, the heavier zippers and more reinforced corner tieouts just seem like more weight in our mind.
On the other hand, it’s hard to argue with a fabric upgrade resulting in a more waterproof product – so for us that aspect is a definite bonus. During wet and humid weather, condensation is there and will need to be managed. Like all silnylon shelters, you’ll probably have to re-tension the Explorer model once or twice to get the perfect pitch. However, the drawbacks are workable in practice and didn’t result in any major headaches.
You can find the Lunar Duo Explorer Tent here at Six Moon Designs and find the heavier but cheaper Lunar Duo Outfitter here. You can also find both tents available here at Amazon.com. For more on how to choose a backpacking tent, see our backpacking tent guide.
Editor's Note: This review originally appeared in Issue 3 of TrailGroove Magazine. Read the magazine article here for additional photos, pros and cons, and our Lunar Duo rating.

For many lightweight and ultralight backpackers looking for a single sleeping bag to suit their needs throughout the year in many parts of the country, a 20 degree bag is often chosen for its blend of warmth while still remaining light enough to easily carry. Here in the Rockies, it might be a bit too warm in the summer, though you’ll still see lows in the 20’s at times at high elevation even in August. For spring and fall the rating is nearly spot-on perfect, and for colder temperatures you can always layer by wearing extra insulation within the bag to push the bag below its rating provided that conditions aren’t too extreme. Of course, it can be nice to have the luxury of several bags to choose from depending on the situation, but for many of us the 20 degree bag makes for an excellent all-around choice.

Western Mountaineering (WM) offers two 20 degree rated bags to fit this niche – the standard UltraLite and very similar but wider and more roomy AlpinLite. Founded in 1970, San Jose California based Western Mountaineering have been manufacturing high quality down sleeping bags and garments that frequently make the short list of any buyer interested in the warmest, lightest, and most packable down gear available. As you might expect with a product that competes among the best of the best in these categories, Western Mountaineering products often come at a price – in the $600 range for the 20 degree UltraLite Sleeping Bag reviewed here. WM fans will tell you that few can compete with the package you’ll receive, however, and in this review I’ll take a look at the UltraLite and share my experiences after several years of extensive field use.

The Western Mountaineering UltraLite is a lightweight, packable down sleeping bag that is made in the USA of ethically-sourced premium goose down.
Specifications & Construction
The UltraLite is a mummy-shaped bag available in the following lengths, with the corresponding weights as stated by the manufacturer:
5’ 6”: 1lb 12oz 6’ 0”: 1lb 13oz (1lb 13.6oz measured) 6’ 6”: 1lb 15oz I tested the 6’ 0” model of the bag, which came in at 29.6oz on my scale. Both the short and medium length share a 59” / 51” / 38” shoulder / hip / foot girth measurement, with the long model gaining an inch in the shoulder and hip areas. You might notice that this bag is a tighter fit than many competitors – WM has elected to keep the fit like this both to minimize weight as well as keep the temperature rating of the bag low without having to add more down. If the bag were larger, more down would be required to maintain the same temperature rating due to the dead air space.
Speaking of down, 850 plus fill power goose down is used for insulation. Fill weights start at 15oz for the short model, and go up 1 ounce each for the medium and long lengths. According to Western Mountaineering, this amounts to 5” of loft, accurate per my measurements. A down-filled hood and collar seal in the heat and continuous baffles (as opposed to sewn-through construction) help eliminate cold spots. The bag is part of WM’s “ExtremeLite Series”, which feature very lightweight shell materials with a DWR treatment. There’s no color choice – the outside is a deep blue color with a black bottom and inner lining. The bag has a full-length zipper with a separate slider on the foot end to allow for ventilation as needed, and a down-filled draft tube inside protects the zipper area from wind and heat loss. The bag is offered in both right hand as well as left hand zip models. All of this packs down into a 7” x 13” package. If you’ve looked around, you’ll know that a 20 degree bag managing to stay under the 2lb mark is hard to find.

The UltraLite's loft measured at 5” in my testing.
Impressions & Field Use
If you’re not buying from a brick and mortar store, the bag will be shipped uncompressed in a large box so there’s no worry of compromised loft. The hand of the fabric is crisp yet soft to the touch, and the bag seems to explode into space from the substantial amount of down fill. When new don’t be surprised if the bag sheds a few feathers that sneak through the fabric with sharper quills. These can be carefully worked back into the bag if they haven’t completely come through the fabric using an inch-worm technique if desired, but the great majority of the insulation is soft down that won’t be able to exit the bag. The sewing and construction is second to none, and after handling the bag you get the idea that WM really cares about the products they produce.
The fit is on the slim side and as a 180lb side-sleeping tester who normally wears a men’s size medium to large t-shirt, I felt the bag worked and was warm and comfortable, but there was little room left to layer for colder conditions. It seems that this weight range / size is about the upper limit for use of the UltraLite in comfort, and the bag is ideal for trimmer users. A lot of this comes down to personal preference of course – a larger bag will give you more room to move and to layer, but will be heavier and dead air space within a bag isn’t a formula for warmth. Another thing to consider is how you sleep. If you’re lucky enough to be a back sleeper that rarely moves during the night, you’ll probably be able to get away with a tighter fit and remain comfortable.

Due to its down construction, the UltraLite packs down to a respectable size.
Western Mountaineering includes a standard nylon stuff sack, but I prefer to keep my critical sleeping gear in an ultralight dry sack for peace of mind. I found that I could get the bag into a 8L dry sack with a bit of effort, but moving up to a 13L size eliminated a bit of stuffing frustration and didn’t compress the loft quite as much on the trail. Arriving in camp the bag quickly attains full loft after being unpacked with a bit of coaxing – a quick shake here and there will help move things along. The baffles are continuous – if needed, you can shake the bag side to side to move down from the bottom of the bag to the top as needed for a little temperature control. The down on the bottom of the bag has little insulation value once compressed by your weight.
Once inside, the bag drapes over your body comfortably, and you can immediately feel the down start to work its magic and trap your body heat. If you get too hot, the full length zipper and separate foot box slider allow for plenty of ventilation options. WM has sewn in a stiffener along the zipper in an attempt to minimize zipper snags (more on that later), and the down-filled draft tube does a good job of preventing a cold spot along the zipper during cold and / or windy weather.

On the warmer nights, the bag works great as a quilt as well – just unzip completely and use the foot box to keep the bag in place. Without the hood and draft collar engaged, and using an appropriately warm sleeping pad for the conditions, I found the bag to be warm to around 40 degrees. Beyond that temperature, the down-filled draft collar, operated by an elastic cinch cord and cord lock, really helps to seal in the heat around your body and prevent the billows effect – where moving around pushes all the warm air out of the bag, leaving a chilly sleeper behind. To reach the 20 degree rating, full deployment of the draft collar as well as the hood (operated by a non-elastic cinch cord and cord lock) will be required. In this mode, you are completely sealed inside the bag save for just a small hole that allows you to breath.

I’ve used the Ultralight in cool to cold conditions during dry as well as humid weather at both high and low elevations, and dressed in normal base layers without adding additional insulation, I found the 20 degree temperature rating to be accurate. You may however, start to feel an occasional chill as the temperature drops to around the 25 degree mark, especially if you move a lot in your sleep. Wearing extra insulation inside the bag, such as a down or synthetic insulated jacket and pants, can help boost the comfort level considerably, especially if the tight fit of the UltraLite allows you to do so without compressing the insulation of the extra clothing or the bag itself. Jen, as a self-confessed cold sleeper, had similar experiences with the bag, but found a 5-10 degree difference in her case – feeling chilly as temps dropped below 30. She also hopes that at some point, WM will offer a women’s specific cut, as the UltraLite’s fit, while quite workable in her case, seems to be optimized for a man’s shape with broad shoulders and narrower hips.

The DWR treatment held up well to condensation, dew, and light overspray into the shelter from heavy rain, and I never had an issue with the down insulation being compromised due to moisture, even in very humid environments. Western Mountaineering states that extra care should be taken due to the lightweight fabric that’s used for their ExtremeLite Series, but the bag has held up very well without special care – although the bag was always used either inside a tent, shelter, or under the stars with a groundsheet. After spending a lot of time in the bag, dirt and oils from your skin will start to effect the loft and warmth, but a quick wash with a down-specific soap and a tumble dry on very low heat with a couple tennis balls tossed into the dryer solved that issue. If you need to reinforce the UltraLite's water resistance after washing, you can apply a spray-on water repellent at home. When not on the trail and in your pack, store the bag uncompressed in a dry place to maintain loft – Western Mountaineering includes a large cotton storage bag for this purpose.
I did have two minor gripes about the bag. One is that when the hood is cinched down, the cinch cord has an annoying tendency to hang down right in your face unless specifically placed out of the way. The other issue is that that even with the sewn-in stiffener along the zipper, I still had issues with it snagging on the shell fabric unless care was exercised.

The UltraLite's zipper does require some thought to prevent snagging on the lightweight shell fabric.
Conclusion
Overall, it’s hard to beat the quality of Western Mountaineering and they are frequently the yard stick that all other sleeping bags are measured against. The UltraLite doesn’t disappoint, and though the price is steep, as a down-filled bag it should last you long into your hiking career with proper care. Depending on your build and sleeping style, it may be a tight fit for many and if you fall into that category, the wider AlpinLite, the 30 degree MegaLite bag, or the 10 degree VersaLite bag may be a good choice. At times I was annoyed with the zipper and hood design, and at this price point I’d like to see little things like that just work. Unfortunately no women’s specific model is offered. In the end however, it’s hard to complain when you’re warm into the 20’s with a bag weighing less than 2 pounds.
The Western Mountaineering UltraLite is currently available in 3 sizes and retails for $600-$635. You can find it here at Backcountry.com.
Editor’s Note: This article originally appeared in Issue 5 of TrailGroove Magazine. You can read the magazine article here featuring the Western Mountaineering UltraLite rating, pros and cons, and more.

In an ideal world that seems to only exist in outdoor gear catalogs, all our backpacking would take place in temperatures that are 65F during the day. Our nights would be a cool and crisp 45F or so. A few delightful sprinkles of rain would occur to add some atmosphere and perhaps a change of scenery to delight photographers. Otherwise there would be perpetually sunny skies with only a few clouds. Clouds to form interesting shapes that materialize as movie characters, castles, or butterflies in our imagination.

It ain't the heat, it's the humility. - Yogi Berra
And no doubt the animals would sing catchy tunes similar to a Disney cartoon and there would be a beer stand greeting us when we finished our trip too. But the world is not ideal. It rains. It gets cold. The wind whips on a mountain pass. Snow becomes slushy and icy.
If backpackers wait for the ideal conditions to backpack, we’d never actually backpack. More succinctly, to again quote the wise sage known as Yogi Berra: “If the world was perfect, it wouldn’t be”. And so it is with hot weather backpacking. The weather can become hot. And sticky. And dry. The conditions are not ideal by some standards. But anytime we have to backpack is precious.
And all conditions are beautiful, challenging, and rewarding in their own specific way. Hot weather backpacking is no different. With the appropriate gear, planning and mental attitude, hot weather backpacking can be a delight.
Hot Weather Backpacking Defined
As with all aspects of backpacking, the term “hot weather” is an elastic one.
Our hypothetical 65F day would be a heatwave near the Arctic Circle. Or the same temperature could be a cold front for daytime temps in the Sahara.
For the purposes of this backpacking discussion, anything more than 85F would be considered hot weather backpacking for anyone used to a more temperate climate. Additionally, hot and humid conditions are often going to require different methods and techniques versus hot and dry conditions.

Backpacking in hot conditions requires extra planning and preparation.
Why Hot Weather Backpack?
In many ways, hot weather backpacking is the mirror image of winter backpacking: the conditions are a bit more challenging and a backpacker has to pay more attention to these conditions.
Having proper hydration, clothing, shelter, sun protection, adequate hygiene, and knowing when the conditions are too extreme for safe backpacking are all aspects of hot weather backpacking that have to be examined.
Much like winter backpacking however, time is too precious to give up to ignore opportunities to be outside. And when the sage smell is carried on a warm breeze, the desert wildflowers are blooming and the reflection of the light from the setting sun is on the rocks, you know why you backpack in the hot weather.

Choosing your footwear for a hot weather hike will have many factors, including terrain and pack weight.
Footwear and Foot Care
For hiking in hot weather, traditional full leather boots are rarely a good choice. Your feet will not breathe too well in addition to becoming very hot. Blisters, rashes, and even athlete’s foot are very likely. Trail runners with excellent ventilation will help keep the feet cooler and allow for air circulation. A lighter sock is suggested for this footwear.
Concerned about debris? A pair of short gaiters will help to keep the shoes clear of pebbles, dirt, and other debris without adding much weight and still allow the feet to breathe reasonably well.
If the terrain is rough, your pack is heavier, or if you are not confident in the use of trail runners, there are many traditional ankle-high boots with mesh material that also breathe well versus traditional leather boots.
Regardless of the footwear choice, socks should be changed at least twice a day. Let your feet air out. Clean your feet a bit with a bandanna, let the feet dry, and then put on a fresh pair of socks.
For multi-day trips, a popular technique is to rinse out the socks and then dry them out on the pack while hiking. Switch to that pair at the next break. For more on footwear selection across the seasons, see our hiking shoes and boots guide.

Proper sun protection is a must while hiking in hot weather.
Sun Protection
While sun protection is very important no matter the season, proper sun protection is a must in hot weather hiking. Besides protection from harmful UV rays, proper sun protection will help keep you cooler and more comfortable while hiking in hot weather. The hiking aspect of backpacking can be prolonged and will be more enjoyable.
Some aspects of sun protection are as follows:
Sunscreen
A minimum of SPF 15 sunscreen is suggested by dermatologists for all skin types. While sunscreen does offer the advantage of being quick and easy to apply, a lot must be carried for multiday trips. Sunscreen may also collect dirt and sweat. Hygiene will be hindered. I find sunscreen is best applied to areas where clothing choices do not protect from the sun as optimally. Some personal examples are the tip of my nose and my cheek bone area.
Headwear
Anything from a simple ball cap to a French Foreign Legion style hat to a wide brimmed hat is favored by many backpackers. I find a hat is superior to sunscreen for reasons noted above. I prefer a wide brimmed boonie-style hat paired with a cotton bandanna underneath. The wide brim protects the ears and the back of the neck in addition to the front of the face. In addition to the sun protection, the evaporative moisture from the bandanna underneath my hat helps keep me cooler. Naturally, a bandanna is also a very handy multi-use item (example of different uses for a bandanna: Washcloth, potholder, first aid, etc.). Soaking a bandanna at a stream crossing and then placing under the hat or even worn around the neck is very helpful in hot weather.
During hot and humid hiking, I find a cotton bandanna is often the only the headgear I need, otherwise I get too hot. The tree cover and some lightly applied sunscreen is typically the only sun protection needed for my head and face in these conditions.

Tree cover, even sporadic and sparse, can offer opportunities to rest in the shade.
Shirts
In hot and dry conditions, a long sleeve shirt helps create a microclimate similar to the bandanna and hat combo above. Your sweat evaporates from the body and the moisture stays trapped inside the shirt. This microclimate helps you stay cooler. Additionally, long sleeves help immensely with sun protection.
A long sleeved button down is more versatile than a light “technical” shirt. If more ventilation is needed, very easy to unbutton the shirt or roll up the sleeves. The collar of a button down shirt also helps with sun protection.
In hot and humid weather, a short sleeve shirt is probably preferable as ventilation is more important than a microclimate to retain moisture. However, hot and muggy weather tends to be more insect prone. The bug protection of long sleeves should not be discounted.
Many experienced backpackers prefer a light colored cotton button down shirt for hot weather hiking over a nylon shirt or similar. My personal preference is for a light colored poly-cotton mix button down; usually a recycled dress shirt of some sort. I find this type of shirt breathes well, dries quickly and is more durable versus a cotton shirt. I have worn nylon button down shirts and have found them inferior to the poly-cotton mix shirts for backpacking. Others may have different preferences.
Shorts or Pants?
Shorts do provide more ventilation versus pants and are often preferable to long pants depending on the hiker.
Long pants, however, do provide more sun protection, creates a microclimate in hot and dry weather and can provide bug protection as well. If there is off-trail travel with a lot of brush or scrambling over rocks, long pants are strongly recommended. I found out the hard way when walking cross-country in Arizona regarding the utility of long pants!!
Handwear
For anyone particularly prone to sunburns, very light gloves are sold strictly for sun protection. A less expensive option favored by some are cotton gardening gloves. Found at any hardware or even grocery stores and only a few dollars. They are not quite as durable as the sun protection gloves but are a more budget minded alternative.

Using an umbrella during breaks can be a great help above treeline or in areas with no shade available.
Umbrellas
Many backpackers find an umbrella to be fantastic sun protection. For breaks and while hiking, the total protection offered by purpose-built backpacking umbrella is favored by many. A dedicated hiking pole user may find using an umbrella difficult. Naturally, an umbrella is not as efficient for more technical terrain.
Sunglasses
Typically when the conditions are hot, intense sunlight is encountered as well. Sunglasses are a key component in sun protection. Sunglasses help block the glare of course. But also protect the eyes from UVA and UVB radiation. There are many sunglasses to choose from and are available from various sources.
A surprisingly good choice for outdoor sun glasses are safety glasses meant for construction jobs. These sunglasses are light, durable, and flexible. They are typically designed with a “wrap around” style for more complete eye protection. And they are often very inexpensive.
Shelters
In hot and dry conditions, I find cowboy camping to be the best method for sleeping outside. With my blanket as the stars above, it is very easy to get fully immersed into nature. A tarp is always packed in case of inclement weather of course. Waking up and seeing the Milky Way above is one of my favorite memories from sleeping under the stars.

Admittedly, most backpackers would not be terribly comfortable with that type of sleeping arrangement. A shelter with ample mesh is suggested in that case. A single wall tent composed strictly of some sort of nylon material will not breathe well and will become very hot.
For hot and humid conditions that are typically insect prone, a similar type of shelter is suggested. Hot and humid areas also tend to have more trees. For that reason, a hammock shelter is very popular in these areas.
Cowboy camping is still possible, but some bug netting should be brought. I’ve used something similar to mosquito netting sold for cots. I then set up the mosquito netting with my hiking poles. At about four ounces, the weight penalty was slight and I was still able to sleep under the stars in the way I prefer.
Sleeping Systems
In many areas where hot and dry conditions are prevalent, the nights can be cool or even cold. Such areas as the Colorado Plateau or the High Plains are high in altitude and will lose heat at night. A sleeping bag or quilt with a lower temperature rating will often be needed. A corresponding sleeping pad with a good R-value (how well a pad insulates; the higher the number, the better) will also be required.
Conversely, in hot and humid areas, the nights often stay warm and do not cool off. A lighter sleeping system is optimal.
Sleeping Bag or Quilt
In hot and dry areas with the typically cooler nights, a 30F rated sleeping bag or quilt seems to fit a wide range of conditions. Colder sleepers may want a sleeping bag or quilt rated for lower temperatures.

In hot and humid conditions where the nights do not typically cool off, a 40F bag or quilt is not only adequate but usually preferred. Synthetic insulation more tolerant of humid conditions versus down insulation and is a choice for many in these types of conditions.
In both hot and dry or hot and humid conditions, I personally prefer a quilt since I can ventilate a quilt more on hot nights. Additionally, I can layer with clothing more effectively on colder nights.
Sleeping Pads
A shocking surprise to many people is how cool the hot and dry areas, typically found at a higher altitude, may become at night. A blow up air mattress with an R-value of 1 is usually not enough. A closed cell foam mattress is light and has enough of an R-Value to be adequate. Naturally, other sleeping pads with higher R-values will work.
Sleeping in hot and humid conditions? A pad is typically brought more for comfort than insulative warmth. If using a hammock shelter, a light or even no underquilt is more than adequate.
Stoves, Cooking, Food and Hydration
Stoves and Cooking
In hot weather conditions, the stove of choice may not only be dictated by the weather, temperatures or personal preferences but also by current fire conditions. In the increasingly fire prone American West, Esbit or alcohol stoves have become restricted in their use during times when wildfires are prevalent. Needless to say campfires or wood burning stoves are banned in the backcountry during these times, too.
White gas and canister stoves are the choice for stoves during these fire bans. Canister stoves are lighter but less efficient for group use versus white gas stoves.
Another choice is to simply go stoveless. Less water is needed when dry camping and a cold meal is sometimes preferable if the day has been particularly hot.
For hot and humid conditions, the choice of a stove comes down more to personal preference more so than any restrictions in place. There are exceptions. But those restrictions are rare compared to the drier American West. So far.

Be mindful of fire restrictions, particularly in hot, dry environments.
Food
The choices of food preferred for hot weather hiking is not that different from three-season backpacking. The exceptions are that I generally try to avoid anything that will easily melt in my pack such as chocolate bars or food that is particularly heavy on the stomach such as certain types of cheese or meats.
What I do prefer more so than other times of the year is salty food. Chips, pretzels, and similar are all something my body craves as I am sweating throughout the day.
Hydration
Rather intuitively, most of us know to drink water when hiking in hot conditions. I find a conservative rule of thumb is to pack a liter for every five miles hiked between water supplies. Add a two-three liters if dry camping (not camping near a water source). Obviously this rule of thumb changes based on the person, exertion levels, or temperatures. But I find it is a rule of thumb that works for many people.
One issue to be aware of is hyponatremia. Essentially, drinking too much water without enough salt intake. Hyponatremia rarely happens to most backpackers if eating the typical food carried for meals and snacks. For the hikers that blur the line between ultra-running and fast hiking in hot weather, hyponatremia may be more of an issue.
Though heavy, sports drink powder is found to be helpful. Besides providing electrolytes and salt, the sports drink powder will make water more palatable and encourage hydration.

Finally, in the hot and dry areas many cactus, prickly shrubs, brambles, or similar abound. A hard sided water bottle or two versus a soft sided container is preferable as a primary water container. More than one backpacker has had a bad encounter between a cactus and their soft sided water container that did not end well.
A large soft sided water container safely inside the pack is usually fine for hauling extra water however.
Rain Gear
As odd as it may sound, adequate rain gear is important to pack during hot weather conditions.
In the high altitudes found for most hot and dry areas, a rain storm the moves in suddenly can cool things off rapidly. Rain gear is needed as much for warmth as rain protection. Light rain gear, pulled out only as needed, works well. A windshirt and umbrella combined is another option popular for many on-trail situations.
Hot and humid? The rain is often welcome relief. Rain gear rarely breathes well in these conditions. I often prefer to get wet from the rain rather than wet and hot from my own sweat. Still, be sure to pack some rain gear in case a cold front moves in and the weather does become cool and wet.
Pack
For hot weather hiking, no particularly special pack is needed.
The only caveat is that during hot and dry hiking, and the scarce water resources that typically accompany this type of hiking, be sure to have a pack that can haul the bulk and weight of the increased water capacity needed.

Other Hot Weather Hiking Tips
Start the day when the weather is cooler. A desert sunrise is also beautiful and more wildlife is out. Adopt a “siesta strategy”. Take a break in the middle of the day when the heat is at its peak. Perhaps eat your larger meal at this time. Hike again when the day is cooler and into twilight. Hiking into the desert twilight? Magical. In hot and humid weather in particular, personal hygiene is very important. While dirty hiker trash is often used a sign of affection amongst thru-hikers, it is not good to be literal dirty hiker trash. Sponging off at night helps prevent rashes, chafing and what is colloquially known as “monkey butt”. As funny as the name may sound, an inflamed part of the body due to inadequate hygiene, sweat and salts is not funny at all. It is rather painful, actually. Keep your feet as clean as possible too during hot weather hiking conditions. Athlete's foot and the resulting dry and cracked skin is not a comfortable predicament. Even with proper hygiene, rashes and chafing may happen. Body Glide or similar rubbed along the thighs help prevent this predicament. And if you do come down with monkey butt? There’s an ointment for that, too. As with extreme cold weather, please do not hike in extreme heat if it can be avoided. Know your limits. Less miles hiked per day is preferable to getting yourself in a medical emergency. Heat exhaustion or even heat stroke are real possibilities if not paying attention. Hike when it is cool, stay properly hydrated and do not exert yourself beyond your capabilities. Final Thoughts
Hot weather hiking is another marvelous way to see the outdoors. Whether it is seeing the dogwoods bloom in the southern Appalachians or seeing the first sego lilies blossom on the Colorado Plateau, nature reveals itself in special ways during this time.
All seasons should be embraced and not avoided for experiencing the outdoors. The outdoors experienced without once smelling of sage in the desert air or the fragrance of thick vegetation of an ecosystem thriving with life? It is an outdoors life that is missing some wonderful memories.
Hot weather hiking has its challenges. But it also has its beauty. With adequate gear, preparation and the proper attitude, hot weather backpacking will enrich the experiences had in the outdoors for anyone.
Editor's Note: This article originally appeared in Issue 28 of TrailGroove Magazine. You can read the original article here.

With a market full of competitors, choosing the right daypack for your needs can be a difficult task. In this review, I’ll evaluate the features and performance of the smallest pack in the popular REI Flash series – the Flash 18 (18 = 18 liters / 1100 cubic inches). In a sea of competing daypacks this is one pack that has managed to stand out for the past decade plus, partly due to its competitive price point. However, with an attractive price I of course always have my concerns – sometimes in the backpacking world budget priced gear can often result in a solution much heavier than competing products and lacking in features that you may find yourself longing for down the road.

The REI Co-op Flash 18 backpack is a minimalist, lightweight daypack that has proven to be reliable over the years.
Flash 18 Features
Personally, I hate excess gear. Don't get me wrong – while I love cool stuff as much as the next person – if I could own one pack that will get me through every situation, that's the way I'm going to lean. At least at first. I tried this out for a while, until one day many years ago when I found myself lugging around a pack designed to carry 10 days of supplies to my favorite Saturday getaway. It became apparent that gear can't always be viewed in black and white terms. My pack was woefully empty, stays and load lifters there yet serving no purpose. It felt like I was using a semi-truck to bring home a few flower pots. I needed something clean, cheap, and functional. Plus…I gave myself a great excuse to try out some new gear. So after hitting the local REI, I walked out with a Flash 18, which has been a frequent companion since that time. Over the years REI has released incremental updates and changes to the Flash 18, however the baseline has remained mostly the same: 18 liters of top-loading storage, lightweight hip belt, shoulder, and chest straps, and an overall minimalist design. In this review we'll look at the basic design of the pack and how it has worked for more than the past decade.
Once I got my hands on the Flash 18, the tags came off and the pack hit the digital scale. REI listed the pack at 11 oz and my pack met this mark exactly. This is a bit heavier than the original version of the Flash 18 – which while listed at 10 oz, came in under spec at 9.3 oz. The pack is extremely simple and clean, with just one small exterior pocket on the latest version. A twin row of webbing daisy chains run the length of the exterior, with one larger "tool loop" at one bottom corner. These don't offer many options for carrying gear outside the pack without some ingenuity, but with a small time investment they can be used to greatly add to the usability of the pack. The newer versions of the pack have done away with the rows of daisy chains and instead use 4 loops to allow securing additional gear. Whether this is an upgrade or downgrade is up to personal preference.

The pack is top loading, and in addition to the large interior compartment you'll find 3 additional pockets. The hydration pouch is found along the back panel, with a small loop sewn into the top should you wish to secure the top of your hydration reservoir to prevent sagging when low on water. The hydration pouch itself easily accommodates a 3 liter Platypus Hoser. Above and centered between each top shoulder strap attachment point, a weather-shielded opening for your hydration hose can be found. The pack has a padded back panel that's removable, (doubling as a sit pad according to REI) so behind the hydration sleeve you'll find the back panel pad compartment. The compartment closes to secure the pad using a thin hook and loop closure. The pad itself is quite thin measuring only 5 millimeters thick, and at .3 oz, is very light. REI has included a zippered pocket on the Flash 18 (great for keys) for some time, originally on the inside but most recently, and perhaps more conveniently, this is now located on the side of the pack.

A drawstring closure is used to close the main compartment, and a small flap covers the opening when cinched. This isn't weatherproof by any means, but if used with a pack liner you should be set for rainy conditions. A slider allows you to easily close and loosen the top drawstring.
The hip belt utilizes 1” webbing, with ¾” in use for the sternum strap. Each strap closes using conventional plastic buckles. The sternum strap buckle also features a convenient whistle, and the sternum strap height is adjustable. The sternum strap and hip belt can both be quickly and easily removed if desired, which will shave off 1.9 oz. Shoulder straps use a different material – relying on lightweight honeycomb nylon mesh that adds a very small amount of perceived cushioning. The ventilation of the mesh is excellent, and serves well to keep the wearer cool in hot weather.
The pack body itself is constructed of 70-denier ripstop nylon, of which you have several colors to choose from. This fabric has a much heavier feel than silnylon, but is still quite lightweight. Starting with the 2nd generation Flash 18, REI began enhancing the pack with water resistant fabrics. Currently, the pack utilizes a nonfluorinated durable water repellent (DWR) finish. In practice I found that water would not penetrate the fabric, but water is still able to penetrate the seams. The fabric is able to withstand moderate abuse, and you may need to be careful hiking with the pack in rocky areas or off-trail where you might encounter a few tree limbs reaching out to snag the fabric.
Flash 18 on the Trail
The usability of this pack is excellent – with one caveat. Since the simple and elegant approach that REI took with this pack eliminates all outside pockets that can hold a water bottle for drinking on the move – I found that hydration system users should be quite satisfied. If you prefer a bottle approach and won't be able to adapt to a hydration system for use with this pack, you may walk away unhappy and the addition of at least one side pocket to hold a water bottle or two would have been appreciated by many users. On the other hand, one outing with the pack involved a day trip fly fishing for 8 hours along a local stream. The pack easily swallowed breakfast and lunch, leaving plenty of room for photography and rain gear. The slim profile allowed for a complete range of motion as I snuck through the streamside brush and dipped under fallen trees – something outside pockets may have hindered.

When turned inside out the Flash makes a stuff sack for longer expeditions – allowing for a summit pack or daypack to range with from base camp when needed. However, at about 11 oz, the Flash makes a heavy stuff sack. If you're simply looking for a daypack to take along with you on longer trips to explore away from base camp, lighter options exist.
Additionally, the removable back pad panel doubles as a sit pad according to REI, but I found the pad to be on the small side for this type of use. Since it's so thin, it also doesn't really add any cushioning and durability is a concern – I had several holes in the pad just from the first use. I was hoping that the foam back panel might add a bit of rigidity, perhaps forming a frame of sorts allowing us to stretch the comfortable carrying limit of the pack, but it's quite floppy and doesn't really add any structure. If you're using the pack without a hydration reservoir, you might find that the panel takes the edge of any sharp or pointy objects contained within the pack, but when used with a hydration system the reservoir itself served that purpose for us and I left the pad at home.
At this point it should be safe to say that the Flash 18 is an admirable day hike performer, but can its limits be stretched? Absolutely. For just a few dollars, a 5 minute time investment, and less than a 1 ounce weight penalty a shock cord system can be added to the outside of the pack to greatly increase its “range”. Here I'm using about 8’ of 1/8” shock cord and one properly sized cord lock. This allows you to carry whatever you please and should enable most ultralight packers to easily use this pack on mild 3-season overnight trips and possibly longer, simply depending on how light you pack and how much you gear you can manage to carry outside of the pack. The latest models have unfortunately gone away from using the daisy chain but external bungees could still be added to the four loops that are in their place.

The REI Co-op Flash 18 backpack fully ready for an overnight jaunt with gear, water, and food
How does the pack carry? Quite well assuming you don't push its limits. I was generally comfortable packing weights up to about 15 pounds. Up to about 20 pounds the pack was manageable but comfort began to suffer. The minimalist hip belt is actually able to perform some load transfer when the pack is tightly packed, or when a sleeping pad (of thicker and denser foam than the included panel) is used internally to create a virtual frame. However, above the 15 pound mark the hip belt became unable to offer any type of noticeable load transfer to the wearer's hips. Some users may wish to remove the hip belt and sternum straps to lighten the pack even further, but I found them critical not only for carrying loads comfortably as just described, but also for securing the pack tightly when engaging in highly mobile activities like off trail hiking or mountain biking.
Per the REI specs, this pack fits torsos in the 15-21” range and with a hip belt range of 26-42 inches. I was able to push the pack with a longer torso comfortably at the low to mid weight ranges, but if you'd like to push to weight limits of this pack longer torsos should shy away. At the higher weight ranges, tightening of the shoulder straps becomes necessary, raising the hip belt uncomfortably high for longer torso users. Hopefully, REI will release multiple sizes in the future.

While the REI Flash 18 offers great features, it is only available in one size, and for those with longer torsos, a larger size (although not currently offered) would be ideal.
Comparison to Earlier and Later Models
As you would expect, the price of the Flash 18 has gone up over the years, and REI had implemented quite a few changes along the way. The pack is currently listed at $49.95. The first model was listed at 10 oz, but came in impressively under-spec at 9.3 oz. The weight of my pack from 2012 tested at 11 oz, and the newest pack is listed at 9.5 oz. All versions of the Flash 18 allow customization that can get the weight down even lower, but you'll have to lose the functionality of the chest strap, hip belt, and foam back panel to make that happen. The shoulder straps are slightly wider than the first generation and are woven into a honeycomb pattern that offers a bit of padding, and I did find this pack more comfortable and stable on the shoulders than the earliest versions.
The closure system was updated with a slider buckle, and the entire system was easier to understand than before. However, I found that the older version was easier to open and close in a single motion. Also, a loop has been added above the hydration sleeve – clip your reservoir in here if you want to prevent sagging as you drink.
The foam back panel and matching sleeve using a Velcro closure were added, and the interior pocket system has been improved. The 2nd generation's interior pockets were on the opposite side of the hydration sleeve and included one larger sized but zippered pocket that sat near the top of the pack. For extra security, it also had a ribbon and clip that sat within the pocket for your keychain or other valuable items. The current models have two interior slip pockets on the same side as the hydration sleeve, while there is an added exterior zipper pocket. This newer version's zippered pocket is located on one side of the pack, allowing phones or snacks to be more accessible while hiking while keeping a sleek profile.

The REI Flash 18 backpack features a ripstop nylon fabric that is treated to repel water.
Conclusion
Overall REI has it right with this pack. Simple value. Currently retailing for about $50, you'll be hard pressed to find a pack in this category, this well built, for a better price. Granted, there are a few drawbacks, but they are workable drawbacks and don't apply to every user's style. REI has added some features over the years, but luckily the Flash 18 has remained a true minimalist daypack. I feel that the best part of the Flash 18 feature set lies in its low price and simplicity. However, it's hard to complain about this much usability at such a great price.
The REI Co-op Flash 18 backpack retails for around $50. You can find it here at REI. For a little more capacity, a top lid, and side pockets, the Flash 22 daypack is also worth a look. You can additionally view REI's full selection of daypacks here.
Editor's Note: This article originally appeared in the first issue of TrailGroove Magazine. You can read the magazine article here, which features additional photos, as well as our REI Flash 18 rating, pros and cons, and more.