This is a new Lock-Up Premium Total Encasement Mattress Cover.  Size: King Features a durable, yet waterproof terry cloth fabric cover and a double knit body with a waterproof inner membrane. A zipper lock feature prevents bed bugs and dust mites from getting to the mattress, creating an impermeable barrier to mold and bacteria. This total encasement bed bug proof mattress cover also provides allergy and dust mite protection, is breathable to help reduce heat buildup, and silent for a safe and sound sleep!  Expands to 18" high.