The Dream On Me 40R 4 Thick Round Crib Mattress is unique in its circular shape measuring 42 in diameter and firmly supports your baby for a restful sleep. This mattress is constructed with quality materials featuring a cloth boarding binding. The 4 foam core is enclosed in a fully washable fire retardant antibacterial hypoallergenic triple laminated cover that aids in the prevention of mold mildew and odor. This mattress fits The Dream On Me Posh Sophia Circular Crib and most standard round cribs. Wipes clean with warm soapy water. Passes all flammability tests (16 CFR 1632 /1633) and also passes phthalate lead and toxicity tests.