From Mattress Firm: Hypoallergenic Mattress & Pillow Protector Set is made of light weight materials which allows for constant air flow, and features a brushed fiber surface which quickly dissipates and evaporates moisture to ensure a cool, comfortable sleep.  Waterproof coating acts as a barrier to keep your mattress fresh from dust, dust mites and other allergens, as well as liquids and stains. The performance material is naturally anti-microbial and will not trap moisture and bacteria. Fits mattresses up to 22 inches deep.