Product details: MicroX polyester insulation has a tremendous warmth-to-weight ratio and continues to insulate even when damp; you'll enjoy the lightweight, low-bulk comfort it provides Double-layer construction increases loft and eliminates cold spots Rated to keep you warm down to about 20°F for comfort on 3-season backpacking trips Bag features a durable ripstop nylon outer and soft polyester lining Full-length draft tube keeps cold air from penetrating the durable 2-way zipper The ALPS Mountaineering Blue Spring 20 Sleeping Bag includes a compression stuff sack