This twin waterproof mattress bed cover fits on a standard twin mattress. Place your fitted sheet over the mattress & waterproof bed cover to secure. When the season hits of bed wetting, potty training or the flu protect your mattress with this mattress pad. This cover is reusable and can be easily wiped clean or soaked in warm soapy water and rinse then hand to dry. Do not place in washing machine or tumble dry.