California King Hardside Waterbed Cover (Evolution 3500) Vinyl Plush lyocell cotton quilted pillowtop cover, Patented tri-zone lumbarpedic quilting Machine Wash or Dry Clean Thermal bonded hypo-allergenic fiber quilt fill, and a Built-in patented super thick vinyl safety liner Insulating properties retain mattress temperature and the Zip-off cover provides easy access to mattress. Provides barrier between mattress and decking, Assists in keeping waterbed sheets in place.