AllerEase Organic Cotton Cover Allergy Protection Waterproof Mattress Pad, Full Cotton Expandable sidewalls are made from 100% Polyester ; 100% Breathable organic cotton cover provides natural allergy protection Waterproof layers are made from quiet thermoplastic polyurethane (TPU) Waterproof protection prevents liquids, urine, spills and stains from contaminating and ruining your mattress Allergy defense fabric blocks dust mite matter and other nonliving allergens from collecting in the mattress pad - these allergens can trigger asthma and allergy symptoms Mattress pad stretches to fit mattresses up to 18" deep Recycled hypoallergenic polyester fiber fill provides comfort and support while reducing the risk of an allergic response