The chill crib mattress by Bundle of Dreams is a 6-inch, 2-stage. It is designed with extra firm support for an infant and a comfortable plush side for your growing toddler. Studies have shown that sleeping cooler helps people sleep better. We have applied this concept to celsius. This 100% breathable mattress not only helps regulate temperature by allowing airflow, in addition, but it also has a dual-sided cover consisting of cotton and our unique cooling celsius fabric. The cooling celsius fabric is made from Tencel and glacier cooling yarns for temperature regulation. The reverse side has a water-repellant cotton fabric. The mattress cover is reversible, removable & machine washable. In addition to the cooling fabric, this mattress has a Prop 65-compliant water-based, cooling application applied to the extra firm layer on the infant side. There are no VOCs, no off-gassing (that chemical smell when you open a mattress with foam), and no toxic emissions. Around the entire perimeter of the mattress, is a 2-inch, firm edge guard to support children as they begin standing. All materials used are eco-friendly, hypoallergenic, and breathable. GREENGUARD Gold Certified. Fits all American standard-sized cribs and toddler beds.