Designed to fit the unique oval shape of the Stokke® Sleepi™ Bed, Naturepedic's crib mattress has been carefully calibrated for both maximum comfort and easier cleanup. The organic cotton and foam core is cushy yet supportive for growing bodies, and has a wipe-clean waterproof surface made from food-grade sugarcane. It's wrapped in a cover with a 3-dimensional woven fabric that lets air flow through, as well as a thin waterproof backing that provides extra protection from leaky diapers.