The Sealy Cotton Cozy Rest crib mattress offer two-stage dual firmness that grows with babies through the toddler years. The mattress has a firmer infant side plus a softer toddler side of cotton and hypoallergenic cushioning. The core is sturdy with a premium posture supportive 204 interwoven steel coil system that is firm, durable and supportive for a lifetime. The full perimeter steel frame supports the entire edge system plus corners and sides are protected by the EverEdge strength pillars. An anti-sag weight distribution frame keeps infants supported. A luxurious cotton cover is natural, breathable, PVC-free and easy-clean. The cover is enhanced with a waterproof and stain-resistant coating to help prevent allergens, mold and odors from spreading.