This Organic Organic Oval Mattress Stokke Sleepi Crib has a Waterproof Organic Cotton Cover. It features a luxurious organic cotton fabric with a clear 100% polyethylene food-grade waterproof coating. Non-allergenic and easy-to-clean. Organic Cotton Filling Pure, Natural, and chemical-free Firm Support Features Air-Core™, a non-toxic environmentally friendly support layer made from 100% food-grade polyethylene. Air-Core is a network of closed-cell air pockets that provide a firm and comfortable base without the toxic properties of polyurethane foam and the allergenic concerns of latex rubber.