Every inch of the Newton Baby Crib Mattress was designed with your baby's health, safety, and comfort in mind. The innovative design is proven to reduce the risk of suffocation and allows air to flow freely for optimal breathability and temperature regulation. Newton's perfect level of cushy firmness helps your baby stay asleep so you can too. The patented Wovenaire core is made of 90% free air - yes, air and 10% food-grade polymer. The Newton Baby Essential Crib Mattress measures 52" x 28" x 4” and is designed to fit all standard size cribs.