The Slick Rock is the only sleeping bag in the ALPS Mountaineering line that uses PrimaLoft insulation. PrimaLoft is a synthetic insulation, but is the best synthetic on the market, making it the most compressible and lightweight synthetic. The Slick Rock uses #8 separating zippers and also uses a 2-layer offset, which are both features that are a must for a good sleeping bag. There is an insulated chest and zipper baffle to keep cool air out and your warm air in.PrimaLoft uses ultra-fine and multi-diameter fibers, which absorbs less water and keeps you warmer whether it's wet or dry. Features:PrimaLoft 2-Layer OffsetMultiple Sizes & TemperaturesInsulated Chest & Zipper BaffleIncludes Compression Stuff SackSpecs:Outer Material: 300T Round RipstopOuter Color: Green/BlackLiner Fabric: 300T NylonLiner Color: BlackTrim Color: RustShape: MummyZipper: #8 Separating Dimensions: 31" x 86"