Crate mattresses  are made  with a  heavy duty canvas or a heavy duty wipe clean material, they are both water repellent, each mattress is made in sections (like a lilo) and each section is stuffed by hand to capacity with a high grade stuffing, they will not go flat, the cover can be either fleece, supersoft fleece or faux Italian sheepskin, they are easy to get in and out of the crate door as the can be rolled up.