After scouring the market, we can confirm that SD’s claim is true: This is the lightest 15°F bag you can get. How’d designers do it? First, they used premium 850-fill down and a wispy 15-denier nylon shell. Then they took a ruthless approach to trimming excess weight, eliminating any feature not directly tied to warmth. They shortened the zipper to 25 inches (it’s hip-high) and pinched overall dimensions by about 10 percent compared to SD’s other 15°F bags.
The noggin-hugging, jacket-style hood shaves material weight without sacrificing thermal efficiency. “It’s not claustrophobic at all,” raved one 5’10”, 150-pound tester after using it in the Tetons. “Still, don’t expect to spin around inside,” says another tester who used it for a week in the Swiss Alps. “The bag moves with you when you roll over.” Cold-sleeping testers wished for a draft collar, saying they felt chilled with temps in the 20s, but warm sleepers didn’t miss one. It’s not, however, the bag to take if you’re planning a bivouac.
The shell fabric sacrifices weatherproofing in favor of weight savings, and the draft tube is sewn onto the bottom side of the zipper (gravity pulls it groundward, so it doesn’t always rest behind the zipper to prevent drafts). As for compressibility and price, a tester in Alaska nicknamed it “Big Gulp”—as in, you could stuff it in a 32-ounce cup, and the cost is hard to swallow. $440; 1 lb. 14 oz.; 15°F