The Lux 12" Gel Memory Foam Mattress features open cell memory foam which is much more breathable and durable than closed cell memory foam. Closed cell memory foam has air bubbles trapped in the cells and will “pop” with pressure which will cause memory foam to sag over time and feel hot! Open cell memory foam will last much longer than lower quality closed cell foam! It is certified to meet or exceed CertiPUR standards which ensures that foams are emissions and content tested, it is made without prohibited phthalates, ozone depleters (CFCs), mercury, lead or heavy metals, formaldehyde, methylene chloride, PBDEs and it is durability and performance tested. The Lux 12" Gel Memory Foam Mattress has a removable zip-off anti-microbial luxury cover.