Slumberjack Big Timber 20 Degree Synthetic Sleeping Bag Shell Fabric: 100% Cotton Liner Fabric: 100% Cotton Insulation Type: 100% Polyester Fiber Temp Rating : 20 / -7C Insulation: Slumberloft Synthetic Weight 9lb 2oz Two-layer, off-set construction and differential cut prevents cold spots Draft tube along zipper keeps out cold air and prevents heat loss along the zipper