So what is the 365 sleep system you ask? It's just the best sleeping bag you'll ever own, that's all. The 4-layer design allows you to use it all year long! From warm summer nights camping with the family, to ridiculously cold winter hunts while being snow trapped in a wall tent, this bag is built to keep you warm and comfortable. Our high performance 300D poly/canvas material is the only option with this bag. This fabric is abrasion resistant, mold & mildew resistant, and has a PU coating for optimum wind and water resistance, while also providing maximum breathability. Layering provides comfort temp range from +35 to -20 Durable 300D polyester canvas shell Soft and comfortable cotton flannel liner High-loft HolloFiber insulation Rugged #8 zipper with lifetime warranty 40" x 90" finished size Weighs 19 lbs Roll-up hood with organizer pockets sewn in