Nylon RDS-certified, 750+ fillpower goose down with a non-PFC Ultra-Dry Down treatment to stay drier in damp conditions Free Flow Zip System offers excellent temperature regulation and multiple sleeping bag configurations Women's specific fit means more narrow at the shoulders (for reduced weight) and wider between the hips and knees to allow for a natural, side-sleeping position Anatomical footbox is constructed for improved warmth retention Lightweight 20D recycled nylon shell with a non-PFC DWR finish to protect against wind and moisture and a 20D recycled nylon liner for greater comfort, Box baffle construction throughout with vertical baffles in the torso to minimize down shift and maximize the retention of warmth, Sea to Summit Guarantee is offered for the Lifetime of this product, In colder temperatures, cinch down the technical hood, zip up the draft-tube protected zippers and allow the 750+ Ultra-Dry Goose Down to keep you warm. As temperatures rise, unzip the Free-Flow Zip system for additional ventilation or completely unzip to be a quilt for use during the extra warm nights. The Ascent sleeping bag is one of very few true three-season backcountry bags available. You can even close the snaps at the shoulders, open the footbox zipper and wear the Ascent at camp giving you real freedom on your backpacking adventures.