A mattress protector is an item of removable bedding that sits on top of, or encases, a mattress to protect it. Aalingans 100% Waterproof Mattress fitted sheet keeps your mattress Protected. This mattress protector Terry creates a healthy, anti-allergy sleep zone. Cotton cover is soft and comfortable to sleep on. It also features a miracle membrane - a polyurethane film that allows your mattress to breathe but creates a barrier that keeps dust mites, bacteria and liquids out.