Cocoon mummyliner silk ultramarine blue a mummyliner is an extremely lightweight tapered sleeping bag liner our high quality silk is the optimum fabric for minimizing packing size and weight silk is soft against your skin and responds well to changing temperatures it feels cool in the summer and is warm in the winter mummyliners made of silk are easy to hand or machine wash and dry quickly woven with a grid like structure of strong silk threads ripstop silk is more durable and resist