Pillow protectors are very common in the bedding industry. They are made to cover pillows and other bed items like comforters, duvets, sheets, and mattresses. They often come in the form of a fitted case that has a zipper on the top. They typically have a zipper on each side and on the top, thus allowing you to easily remove or add items. Pillow protectors are usually made with polyester material and they are also breathable.