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.