You both will sleep more soundly when your baby rests on this Serta? Perfect Sleeper? Deluxe Crib Mattress Pad. With a soft, 100percent cotton quilted top, this mattress pad, which fits standard crib mattresses, keeps your little one comfy. Meanwhile, the 100percent waterproof underside means this crib mattress pad protects the mattress from leaky diapers, spit-up and spills. This waterproof mattress pad, which has an elastic edge for a snug fit, is free of PVC and phthalates, too. Gender: unisex.