Think of this hoodless 800-fill down bag as a really warm blanket: perfect for adventure racers and others who like to hike more than sleep. After using it on cold fall nights in the Southwest, testers called it warmer than other comforter-style bags they've tried, but advised that you'll still need to wear all your layers–and warm ones–in temps below 35°F (that's why we deem it a summer bag despite the 20°F rating).
Two removable straps wrap underneath a sleeping pad (there's no bottom insulation) and adjust for body size, clothing, and draft resistance–though it's hard to seal sides completely against the chill. Bottom line: True zealots will love the Ultra's scant weight and liter-bottle packed size, but everyone else will wish it actually was a bag. $225; 1 lb. 3 oz.; 20°F