The Fashion Bed Group InvisiCase 9 in. Mattress Encasement with Stain and Bed Bug Defense offers a waterproof barrier. this encasement fully surrounds your mattress to help protect from stains, moisture, dust mites, bed bugs, and pen dander. It features a patent pending easy-zip expandable design with removable zippered top for easy cleaning. A Velcro cover over the zipper enclosure provides the ultimate barrier against dust mites, bed bugs, and pet dander. High performance polyester super-stretch fabric is machine washable and fits most mattresses or box springs from 9 to 12 inches thick.