These revolutionary crib mattresses allow your baby to breathe freely through the open-celled topper even if they are facing straight down. The side openings allow air to constantly circulate protecting your baby from harmful carbon dioxide accumulation. The 3D open-celled topper helps keep an infants core temperature stable. Not too hot, and not too cold, resulting in a longer, safer, more comfortable sleep for your baby. The crib mattress topper can be easily removed and laundered in a standard washer and dryer providing a more sanitary sleeping environment for your baby. There is no inner core, so no messy or cumbersome bathtub washing. The base is easily wiped clean while still in the crib.