This Sealy Cozy Dreams Crib Mattress fits both standard size cribs and toddler beds so you can use it for years. This extra-firm mattress offers advanced support with an interwoven, 150-steel coil system. The ultra-thick support layers are breathable and hypoallergenic; they provide the firmness newborns need and the cozy comfort toddlers want. The entire cover and lock-stitched binding is waterproof and tear-resistant.