When minimal weight and maximum warmth are crucial, The North Face Summit Series Inferno 20Adeg provides the highest level of protection and comfort with ultralight 850 fill goose down and durable Pertex Endurance shell fabric. . . . . Premium 850 fill Eastern European grey goose down for excellent warmth to weight ratio and compressibility. Trapezoidal baffles keep down in place and prevent cold spots. Side block chevron V shaped baffles prevent down from shifting to prevent cold spots. Lightweight 20D Pertex Endurance nylon ripstop shell fabric backed by ultrathin membrane for high breathability, wind and water resistance. DWR durable water repellent finish repels moisture on shell fabric 30D nylon taffeta lining. Climashield Prism a synthetic insulation anti compression pads at head, torso, and feet for greater thermal efficiency. Ergonomic hood with drawcord adjustment surrounds head for warmth and comfort. Down filled draft collar to seal in warmth. Vaulted ergonomic foot box allows natural foot movement while retaining warmth. Oversized, down filled ergonomic draft tube along zipper keeps warmth from escaping. Zipper reinforcement for smooth, anti snag zipping. Shoulder level zip watch pocket. Glow in the dark zipper pulls hang loops for drying. Expedition fit for more warmth, less weight and bulk. Compression stuff sack doubles as a summit pack mesh storage bag.