Cocoon mummyliner expediition liner ripstop silk black large use a cocoon ripstop silk expedition mummy liner to protect your sleeping bag investment mummy liners add 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 cocoon mummyliners are specially designed to fit any tapered mummy sleeping bag they feature a drawstring hood