Sierra Designs Diamond Spring 30 Degree Women&#39;s Three-Season Flex Down Sleeping Bag 600 fill goose down Flex technology is designed to eliminate constriction, allowing the bag to move with you, keeping you warm and comfortable Ergonomic Hood is warm and comfortable, and draft tube along zipper insulates against cold spots Ergonomically Shaped Foot Box fits the natural shape of the foot at rest for increased comfort Snag-Free Zipper Tracks, Pad Locks