When it comes to pound for pound comparisons of weight, compressibility, and longevity, down sleeping bags simply fly away from heavier synthetics. The 600-fill power down in the Hotlum is a good compromise between the super expensive down bags and more economical synthetics. The outer shell is 40 denier ripstop nylon, more than twice as strong as some of the featherweight bags out there. It is not waterproof, so use a tent or bivy sack if the skies are threatening, but our testers found it tough enough to survive bivouacs along the rocky Appalachian Trail in Pennsylvania.
The 15°F rating is accurate and owes part of its effectiveness to a full-length insulated draft tube and deep hood with independent top and bottom adjustments. The long zipper opens the bag wide like a quilt for use on warmer nights, and the women-specific cut is not nearly as tight as some mummy bags, giving room to roll around or wear some layers to bed on frosty nights that push the comfort rating. $199; 3 lbs. 8 oz.; thenorthface.com