The Original PeachSkinSheets® Breathable Sheet Sets include one Fitted Sheet, one Flat Sheet, and two Pillowcases with European Envelope Closures. They feature the ultra-soft luxurious feel of 1500 threads per square inch. They are made of a high performance, athletic grade Smart Fabric designed to wick away moisture while regulating cool and warm body temperatures for a superior sleep experience. Fitted sheets are deep pocket with elastic all the way around and fit up to 18" thick mattresses such as memory foam, custom number and double pillow top.