The Sealy SafetyCase Protective Crib Mattress Encasement provides a 100% waterproof barrier to guard against leaky messes and spills and is machine washable and dryer friendly for easy cleaning. The SafetyCase offers a square corner design that fully encases both square and round corner crib mattresses and can easily zip around even the thickest foam or innerspring baby mattress. Use underneath crib mattress pads and fitted crib sheets to create a well-protected and cozy sleeping environment for baby. We recommend that new parents purchase 2 crib mattress encasements, so you always have a fresh, dry one on-hand while the others are in the wash.