Designed with comfort and weight savings in mind, the lightweight REI Radiant 40 sleeping bag has a mummy shape but offers a spacious, relaxed fit. High-quality 650-fill-power goose down is warm, lightweight and compressible ripstop nylon shell resists water and abrasion. Smooth taffeta lining is comfortable against your skin. Exclusive REI Down Fill Calculator optimizes the amount of down per baffle for the most warmth with the least amount of down. Baffle spacing allows the down to remain fully lofted and keeps it from shifting, preventing cold spots. Relaxed fit from the shoulders to the hips increases comfort by providing ample space to move around. Equally distributed insulation all the way around the bag accommodates the multi-position sleeper. Contoured hood, face muffler, draft collar, roomy footbox, full-length antisnag zipper, and full-length draft tube with ground-level seams keep body heat in and cold air out. Differentiated drawcords 1 round, 1 flat let you adjust hood and neck easily in the dark. European Norm EN is an independent third-party temperature rating, allowing accurate comparisons across brands with other EN-rated bags. Includes nylon stuff sack and cotton storage bag.