Gear Review: Sierra Designs DriDown Cal 30

Less is definitely more with this ultralight, which achieved the test’s top marks for quick-to-heat insulating power yet still packs down smaller than some puffy jackets. “The warmth-to-weight ratio is off the charts,” reports one tester, who stayed cozy right down to the Cal’s temperature rating in Oregon’s Salmon-Huckleberry Wilderness. “I thought I was screwed when I unpacked it on a snowy night in Washington’s central Cascades,” says one camper, skeptical that such a light bag could do the job. “But once I zipped up, I was toasty warm within minutes.”

Key ingredients: premium, 800-fill DriDown and vertical baffles, which noticeably speed up heat transfer throughout the bag (even to testers with self-diagnosed “icicle toes”). One tester soaked part of the Cal when he sat on it to change out of wet trunks after a dip in the Pacific: “It was totally dry two hours later, well before bedtime,” he reports. A form-fitting cut means less dead space to heat, and a half-length zipper entirely seals off the bottom half from drafts (and saves weight).

Breathability also impressed, thanks to the translucent-light, 10-denier ripstop nylon shell. Result? Even though the short zipper doesn’t allow foot venting, one tester reports: “Zero clamminess, even at 40°F.” The Cal’s ample-in-the-shoulders, narrower-in-the-footbox girth (62 and 38 inches*) left enough space for the toss-and-turners to move inside the bag, while cold sleepers appreciated the thermal efficiency of the streamlined bottom half. But some testers wished for more lower-body wiggle room. “I had to come all the way out of the bag to change my pants,” gripes a 5’9” tester.

Caveat: Ultralight shell and lining fabric call for careful handling, though we didn’t experience durability issues during four months of testing. $399; 1 lb. 4 oz.; 30°F; sierradesigns.com

Overall: 4.6

Warmth to weight: 4.8

Comfort: 3.8

Packability: 4.9

Water resistance: 4.0

*Dimensions are measured according to standardized methods, but fit and feel vary in the real world, so try before you buy. 

Tester Notes

Elisabeth Kwak-Hefferan: It’s not the loftiest bag—kind of thin, really. But it did keep me warm beyond my expectations.

Dan Larson: Simply the best sleeping bag I’ve ever tried. The warmth to weight ratio was off the charts (up to 11) in my experience. It was quicker to warm me up after climbing into than any other bag. And the packability was amazing. It compresses quite small.

Nick Sutton: I really liked how easy it was to pack down. It was lightweight and was easy to conform to tight spaces. I noticed a little dampness one morning, so I turned it inside out and let it hang out in the sun, which made it dry out pretty quickly.

Eli Zabielski: I think this is one of my favorite sleeping bags I have ever seen. I found the bag to be sort of narrow, to my liking. The lining was extremely nice, definitely the best in the testing rotation.