Bundle of Dreams 5-Inch 2-Stage Mini Crib Mattress is made with an Organic Cotton, removable and machine washable cover. The 100% Breathable mattress not only helps regulate temperature by allowing air to pass through the entire mattress, but there are no VOC's, no off-gassing (that chemical smell when you open a mattress with foam), and no toxic emissions. It's designed for extra firm infant support, and a comfortable plush side for your growing toddler. All materials used are eco-friendly, hypoallergenic, and breathable. This mattress is GreenGuard Gold Certified.