The Western Mountaineering HighLite Sleeping Bag will keep you warm and comfortable down to 35F and weighs a ridiculously light 1lb Reg, making it an excellent choice for ultralight summer outings. Western Mountaineering uses only the best European goose down to build this 850 fill bag. Everything in the HighLites design is intended to reduce weight and increase compressibility including a remarkably light shell fabric, a half-length zipper and a streamlined cut. 20 x 20 denier Ripstop nylon provides even construction for a more downproof fabric, meaning the 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 HighLite features box baffle construction to better contain down and prevent it from shifting to create cold spotsthis is very important in bags with less down, and Western Mountaineering does it best. Youll appreciate Western Mountaineerings meticulous craftsmanship when youre still sleeping toasty warm decades after you purchased this bag.