Protect-A-Bed Allerzip Smooth Twin Mattress Encasement, 9-Inch Cotton Waterproof: Polyurethane film backing repels liquids like urine and sweat on all six sides Breathable Barrier Fabric: NOT hot to sleep on. Allows body vapor to breathe through 3-sided zipper lock is certified barrier for bed bugs, dust mite and allergens. Easy to Wash and Use: Machine washable in warm or hot water. Tumble dry on medium heat. Fits Twin size mattresses 38 x 75 inches, 7 to 12 inch height.