The Gaia Baby Serena Bedside Crib Mattress in White has a fully breathable soft core encased in a luxurious ventilated polyester cover. The zippable cover can be removed and washed at 40c for optimum hygiene. Features Adaptive technology - Treats the textile with a temperature-sensitive polymer and provides a dynamic response: the warmer it gets, the more Adaptive will evaporate moisture. More evaporation means a dryer and cooler sleeping environment.