MontBell U.L. SuperSpiral Down Hugger 0
0˚F | $519 (regular length)
2 lbs. 5 oz. | montbell.us
A good cold-weather sleeping bag should compress to the size of a cantaloupe; it should be true to its temperature rating; easy to get in and out of and cinch well enough to keep cold out and warmth in. Beyond that, a sleeping bag is pretty simple. MontBell, however, would beg to differ.
I’ve been using MontBell’s zero degree-rated U.L. Super Spiral Down Hugger for the last three winters and it’s anything but a regular bag. Its complicated name (let’s just call it the U.L.) belies even more complex construction. Unlike those of a traditional bag, the baffles of the U.L. spiral around your body at a 45-degree angle. That, combined with elasticized fabric and stitching and some classic tailor’s technique, MontBell says, makes the entire bag stretchy. And it is—the U.L. moves with me when I sleep making it both more comfortable and warmer, I think, than a regular bag.
From zipping in, the comfort of the U.L. is obvious. It isn’t restrictive—especially noticeable in the legs—and it’s stretchy enough that I can extend my arms almost fully outward. It feels light, unlike a winter-weight down comforter, but that doesn’t mean it’s cold. Because it’s stretchy, it hugs closely (as its name might imply), which I’ve noticed eliminates spots of dead air. I’ve slept comfortably in the U.L. on single-digit nights on ridge lines in New Hampshire’s White Mountains and toasty nights in western yurts and it will long be my cold-weather bag of choice.
+ The hood is extra lofty and there’s a full draft collar with dedicated face and collar cinches for keeping cold air out.
- It lacks a small pocket that, on other bags, is handy for storing earplugs, a headlamp or a late-night snack.
= True to its rating, ultralight, super compressible and far from confining. The U.L. takes cold-weather sleeping bags to dreamy level.
Big Agnes McAlpin SL
EN Lower Limit: 5˚F
Price: $360 (regular length)
Weight: 2 lbs. 15 oz.
Vertical baffles uniformly distribute body heat across the McAlpin, Big Agnes’s new, 700-fill cocoon that features DownTek insulation, a water repellant-treated goose and duck down.
Rab Neutrino Endurance 600
EN Lower Limit: 7˚F
Weight: 2 lbs. 7 oz.
The widest-fitting option of these four is an 800-fill down bag from British manufacturer Rab. The Neutrino has a water-shedding Pertex Endurance shell and a handy inner pocket placed on the generously sized draft collar.
Sea to Summit Alpine III
EN Lower Test Rating: -4˚F
Price: $649 (regular length)
Weight: 3 lbs. 8 oz.
Sea to Summit’s coldest-rated bag has a highly water resistant outer shell, wide footbox and inner pocket, and stiff “anti-snag lines” prevent the draft tube from getting caught in the zipper. The snuggest-fitting, but warmest, of these four.
Sierra Designs Zissou 0 Hi
EN Lower Limit: 6˚F
Price: $300 (regular length)
Weight: 3 lbs. 1 oz.
Filled their proprietary DriDown—hydrophobic-treated feathers—Sierra Designs’s cold-rated Zissou is weatherproof and ultra affordable. The draft collar is somewhat thin and lacks a dedicated cinch but the bag packs small and is reasonably lightweight.