This mattress turned out to be more than what I had hoped for. Since changing his mattress he has actually slept better, not kidding! The water resistant cover around the mattress is more thin and silky and not thick tough plastic. It provides the right amount of comfort for my little one and has not dipped at all. I do use a thin mattress cover just in case and turn it on a regular basis just for preventative measures. Fits my standard crib and fitted sheets (from Kushies). No complaints!