WATERPROOF COVER: Lab tested to help keep dirt from spreading on the mattress surface. 100% waterproof, stain-resistant, tear-resistant to help keep the inside clean. Easy clean surface! AMERICAN-MADE POSTURE SUPPORT: Engineered with 182 interwoven posture support coils that provide premier support for growing babies plus steel edge supports. Expertly tested for lasting durability and firmness for years of use. 2-STAGE FIRMNESS: 2-Stage dual firmness with firmer side for newborns and infants, plus a cozier side for toddlers with extra foam cushioning. The infant side is tagged for your convenience. SUSTAINABLE AIRY CUSHIONING: Made with Earth-friendlier materials that provide lightweight, airy comfort and support throughout. Sealy crib mattresses and support materials are proudly made in the USA. SAFETY & QUALITY TESTED: Passes GREENGUARD GOLD Air Quality Certification, firmness and durability tests, ASTM, CPSIA, and harsh chemical standards. Snug fit inside all standard full size cribs and toddler beds; measures 51.63 x 27.25 x 5. 5 inches.