Sleep Safe ZipCovers© use a soft cotton-like Evolon® fabric protects against allergens, mites and bed bugs. Medically approved for bed bug and dust mite protection. Evolon® provides superior moisture management. Water such as sweat is absorbed by the fabric then dries very quickly wicking moisture away from the skin. Its filtering barrier comes from a dense compact fiber structure that’s breathable but strong. Because the fabric (not chemicals) protects you, there’s no stiff rustle sound. Washing doesn’t remove its effectiveness and makes the fabric softer. Locking zippers on the encasement guarantee security and efficiency. Our encasements are made in our plant in the southeast USA and come with a 10 year guarantee. Evolon’s® production is also environmentally friendly with numerous health and environment awards to its manufacturer.