The MLILY Harmony Chill is the direct successor of our popular Serene Elite model. It contains a layer of PCM (phase changing material) that absorbs and releases heat throughout the night to keep you comfortable. Harmony Chill 2.0 Comfortable Plush Feel Cooling Knit Cover Phase Changing Material Medium Firm Comfort Memory Series | 13″ Features 1. Cooling Knit Fabric 2. AirCell Technology with PCM 3. Bamboo Charcoal Memory Foam 4. Liquid Gel Flex-Foam 5. Egg Embossed Foam 6. Flex Comfort Foam Base