There s nothing worse than waking up shivering in the middle the night. Add extra warmth to your bag and stay cozy all night long with the Slumberjack Warming Sleeping Bag Liner, Red, Size 80" L x 34" W. Heat Retaining Technology does exactly as promised, keeping the heat in while wicking moisture and sweat away so you can be all toasty without getting sweaty. The soft and stretchy fabric protects your bag and helps to keep it clean. An anatomic footbed lets you sleep naturally, and the fabric stretches to move with you. Stuffs into a durable oxford stuff sack with an easy-carry handle when you re ready to break camp.