The evolution of the sleeping bag is here. With its minimalist, space-saving design, the 20°F(-7°C)Evolution Down 20 will help keep you warm while also being easy to fit in your pack. Features. 600 fill recycled down offers lightweight warmth and a high level of compressibility. Mummy design cuts down on excess material to save weight. Recycled face fabric and lining are durable while still being super soft for a comfortable night's sleep. Fully insulated hood with an insulated cinch collar is designed to seal out chilly breezes and keep your head warm. Trapezoidal sidechamber baffles reduce cold spots and retain loft. Anti-compression pads for better clo values. Smooth, durable Ykk 3/4 side zipper makes it easy to get in and out of the bag and saves weight. Synthetic fill around the toes limits compression and increases warmth for the vaulted footbox.