Sierra Designs Sleeping Bag from $220 to $289, from Altrec.com

You won't believe how much warmth and comfort you get from such a small package - the Nitro packs into a tiny sack (included), but stays toasty to 15 degrees. We build in Flex between the shoulders... more

You won't believe how much warmth and comfort you get from such a small package - the Nitro packs into a tiny sack (included), but stays toasty to 15 degrees. We build in Flex between the shoulders and knees, so you get the comfort and thermal benefits, while saving precious ounces. Continuous baffling and a draft tube contain 800-fill goose down, the warmest, lightest insulation available. less

Going Ultralight doesn't have to mean suffering, because we never skimp on our lightweight bags. We'd rather find a way to shave the weight and innovate on performance, like using Flex technology f... more

Going Ultralight doesn't have to mean suffering, because we never skimp on our lightweight bags. We'd rather find a way to shave the weight and innovate on performance, like using Flex technology for our Nitro 30. We build in Flex between the shoulders and knees, so you get the comfort and thermal benefits, while saving precious ounces. Our smart Foot Box Venting lets you customize the climate in the lower half of your Nitro, without adding the weight of a full-length zipper. Ultralight speed... less

The Spark helps you sleep well, even when the mercury falls to 15 degrees. With Partial Flex construction you'll sleep more comfortably and more warmly than ever before. All without adding noticeab... more

The Spark helps you sleep well, even when the mercury falls to 15 degrees. With Partial Flex construction you'll sleep more comfortably and more warmly than ever before. All without adding noticeable weight! We generously fill the continuous baffle construction with 800-fill down, distributing more through the torso to bolster warmth. The down-filled draft tube and Jacket Hood take a miserly approach to your body's warmth-they horde it greedily! Twenty-denier shell material won't sprout down,... less