ANTI AGING. ANTI SLEEP CREASE. ANTI BED HEAD. SLIP IS THE #1 PREFERRED BRAND OF SILK PILLOWCASES BY DERMATOLOGISTS FOR THEIR PATIENTS, THEMSELVES, AND THEIR FAMILIES. * The beauty secret of celebrity hairstylists, dermatologists and beauty experts. Includes 1 x King / International Standard Pillowcase (20” x 36” / 51cm x 91cm) with invisible zipper closure | Machine washable | See care instructions for details. This product is also available with an envelope closure and in a queen size. *Learn more