Simmons Health Assure Pure Firm Crib Mattress is a wool blend core Crib Mattress that is made from recycled polyester and wool blend core. Wool is a high-quality natural fibre with superior loft and resilience. Wool is naturally anti-bacterial, temperature regulating, breathable and eco-friendly. Thousands of tiny air chambers between the compressed fibres allow air to flow freely for better breathability and a fresher mattress. It is also free of VOC's, as the polyester fibres do not off-gas which can pose a health hazard for a healthier sleep environment. The deluxe organic cotton cover is chemical free for a naturally healthier sleep surface. 2 stage support with a plush 2" wool blend layer on the toddler side for luxurious comfort.