Safety 1st - Grow With Me 2-in-1 Crib and Toddler Mattress: Filling: Polyester Thickness: 5.5 inches Extra firm Fits standard cribs and toddler beds High density thermo-bonded fiber core 2 different firmness levels for ideal support of babies on one side, and toddlers on the other Additional cushioning layer on toddler side for optimal comfort Lightweight and durable for long-lasting use throughout your child's development Outer Cover: Polyethylene Vinyl Acetate (PEVA) PVC-free surface is water resistant and wipes clean Free of phthalates and lead Product Dimensions: 52.5"L x 27.5"W x 5.5"H Flip and Rotate mattress every 2-3 months. Mattress cover needs to fit well (not too tight/loose) over a crib mattress. Need to take care washing covers because they may shrink. Maximum weight 50 lbs. Made for sleeping use only. Jumping may case indentations in the mattress. Meets federal flammability standard 16 CFR 1633 without the use of potentially harmful chemicals The Safety 1st Grow with Me 2 in 1 mattress has achieved GREENGUARD GOLD Certification GREENGUARD Certified products are certified to GREENGUARD standards for low chemical emissions into indoor air during product usage.