Gear up for your next high altitude or colder latitude adventure with the Alpine Down Sleeping Bag. The expedition mummy fit provides ample space for winter gear, while the modified Free-Flow Zip system provides ventilation and versatility. Complex construction throughout and 850+ fillpower, RDS-certified non-PFAS Ultra-Dry Goose Down delivers maximum warmth retention. Design and Details: The technical hood, double draft tubes, expedition cut and 850+ fillpower RDS goose down combine to keep you warm in the coldest of climates RDS-certified, 850+ fillpower goose down with a non-PFAS Ultra-Dry Down treatment for maximum thermal performance Free-Flow Zip System: Full-length zipper with half-length zipper on opposite side for excellent temperature regulation Roomy expedition mummy fit provides plenty of space for you, performance clothing and gear you don't want to freeze Recycled 20D nylon shell material with non-PFAS DWR is light and durable Hood and footbox have a highly water resistant, breathable fabric for extra moisture protection - ideal for bivies or snow caves Highly breathable liner for enhanced comfort Sea to Summit Guarantee is offered for the Lifetime of this product