Cocoon mummyliner silk natural silk a mummyliner is an extremely lightweight tapered sleeping bag linerthe premium quality organic cotton is grown by indian farmers it is then woven into a very lightweight and fine yet durable fabric 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