The MummyLiner Silk from Cocoon adds warmth and comfort to your sleeping bag, while protecting it from dirt and body oils. A MummyLiner will extend the life of your bag by eliminating the need for frequent washings, which is how most bags are damaged. It's breathable high quality silk is the optimum fabric for minimizing packing size and weight.Cocoon MummyLiners are specially designed to fit any tapered mummy sleeping bag. They feature a drawstring hood, a boxed foot end and are double stiched for durability. On a hot night, your MummyLiner might be all you need.