The "2-in-1" Crib Mattress is the most popular option for parents with convertible cribs. This all foam convertible mattress is very lightweight compared to coil spring "2-n-1" mattresses making it easier to lift and change sheets while in a crib. The infant side is made of Colgate's award-winning very firm (pediatricians recommend using the firmest mattress) Classica I foam for superior back support while your child's spine is still weak and developing. The infant side is covered with triple laminated, water-proof, hospital grade vinyl. Once you're ready to convert to a toddler bed, you simply flip the mattress over to the toddler side! The toddler side is constructed of Visco-elastic memory foam for extra support of larger children and comfort as the foam contours to your child's body. The toddler side is cover with damask cloth to allow the visco foam to conform to the body (a water-proof cover is recommended, sold seperately). All Colgate mattresses are out-gassed to remove toxic fumes from the vinyl and use only virgin materials (no recycled product) to eliminate concern of prior chemical or biological contamination that may cause allergies or sickness. Measures 28"x52"x5".