100-Percent Polypropylene Permafresh Complete Mattress protector set, 100-Percent Encasement with zipper closure. Set includes: One Mattress protector, one box spring protector and one 20-inch by 26-inch pillow protector. Permafresh represents a break though in technology. Permafresh uses 100-Percent polypropelene,which is bio degradable. The set contains one mattress protector, one box spring protector, and one pillow protector. Fits mattresses up to 15-inch deep. Safe and water resistant. Machine washable.