From snowy mountain escapes to freezing spring nights in the desert, the Mountain Hardwear Rook 0 Degree Down Sleeping bag delivers lightweight warmth in an incredibly stowable package. Filled with a generous serving of down insulation, it offers lofty heat-trapping performance that's light enough for lengthy backpacking trips, and comes with a compression stuff sack to help you fit more into your pack. Even in the depths of winter the efficient mummy shape works hard to keep you comfortable, and the women's version features added insulation specifically designed for smaller bodies. Mountain Hardwear equipped it with a down-filled face gasket for extra toasty comfort on frigid nights, as well as a two-way zipper in case--on the other hand--the nights aren't as cold as expected.