Simmons Bliss Firm Crib Mattress is made from recycled polyester core. Thousands of tiny air chambers between the compressed fibers allow air to flow freely for better breathability and a fresher mattress. It is also free of VOC's as the polyester fibers do not off-gas which can pose a health hazard for a healthier sleep environment. The Tencel cover made from eucalyptus is naturally anti-bacterial and moisture wicking for a drier and fresher sleep surface. It is two-sided with 2" Eucalyptus Tencel plush layer on the toddler side for a drier and fresher sleep surface.