The Western Mountaineering UltraLite Sleeping Bag will keep you warm and comfortable down to 20F and weighs only 1lb 10oz Reg yes, thats ultra light Western Mountaineering uses only the best European goose down, and with 850 fill, the UltraLite bag is an excellent choice for cold weather camping. 20 x 20 denier Ripstop nylon provides even construction for a more downproof fabric means down is less likely to leak out of your bag like a goose shedding its feathers. A silky smooth taffeta lining is soft on the skin and breathable for climate control inside your bag so you stay warm without cooking your goose. The UltraLite features Western Mountaineerings unique split collar which combines half of a down filled tube with flat fabric and cinches down to seal in heat as effectively as a full draft collar but without the excess weight. Youll appreciate Western Mountaineerings meticulous craftsmanship when youre still sleeping toasty warm decades after you purchased this bag.