Viscose Derived from Pillow Protectors Cool & Breathable: Our zippered pillowcase is made of viscose derived from with High 400 Thread Count, viscose is usually smoother and 3 degrees cooler than cotton and is also thermo-regulating. Keep you cooling and dry all night, even in hot weather. Perfect for hot sleepers & night sweats Smooth & Silky: The smoothness and moisture-retaining effects of viscose pillow case will help your hair glide over it to reduce tension and pulling at night. Enjoy a gentle sleep experience that reduces wrinkles and hair loss for a truly rejuvenating night's rest Convenient Zipper: zipper closure prevents the pillow from sliding out. The durable exquisite craftmanship with neat stitches to make the pillow cover hold your pillow perfectly without moving around. Perfect for Down-feather pillows and any other kinds of pillows Easy Care: This Standard 100 by OEKO-TEX certified pillowcase set is machine washable for easy maintenance. Cold Water Machine Mash with Similar Colors , No Bleach, Tumble dry Low, and cool iron if needed. Viscose derived from may naturally and expectedly shrink after washes. We've increased the size to compensate for the natural shrinkage What you : This pillowcase set includes 4 pillowcases (20" x 30") with a zippered closure to keep your pillows in place and prevent hair from getting caught