Protect-A-Bed Luxury Waterproof Mattress Protector, Twin XL Cool Feeling Sleep Surface: Thermo-regulating Tencel is coolest waterproof protector to sleep on. Tencel Fibers: Tencel is all natural, organic, chemical-free and smoother on skin than cotton. Silky Smooth Feel: Especially helpful for people with sensitive skin, or skin disorders such as eczema. Waterproof: Polyurethane film lining repels liquids like urine & sweat. Breathable Barrier Fabric: Guaranteed NOT hot to sleep on. Allows body vapor to breathe through protector.