The Colgate Eco Classica III Dual Firmness Crib Mattress - EC600F features an extra firm side for the developing infant and a firm side for the toddler. The two pieces of foam in the Colgate Eco Dual Zone EC600F are partially made with plant resins which minimizes the carbon footprint of this mattress. A waterproof organic cotton covers the foam and the barrier fabric. Organic cotton is a very durable material as well as being natural and sustainable. This is the perfect crib for the parent that likes the versatility of an infant/toddler mattress but is more ecologically minded.