SI Exxxtreme Sheets Pillow Case King Size PU (polyurethane) coated nylon. This king-size pillow case, 20" x 36", made of PU (polyurethane) coated nylon material is both super soft and 100% waterproof / fluid proof. Machine washable. Specifically designed to withstand your wildest bedroom play. Can be used with all types of lubricants, including oil-based. Constructed from extra-soft PU coated material they can be used for sleep as well as play! Hook/loop closure.