The Original Cool Slumber Pillow Pad"s ChillGel technology actively regulates your head"s temperature by absorbing heat away from it so that you can sleep comfortably cool all night long. ChillGel creates a thermal break between you and the pillow to absorb body heat into The Original Cool Slumber Pad rather than storing it in the pillow and transferring back during sleep. The result is a comfortable sleeping body temperature all night long, without the need for plug-in devices, water or refrigeration of any kind. Pad temperature will vary depending on your body temperature and pressure on the pad. Care: Do not machine wash or dry; spot wipe if needed. Excessive heat exposure will prevent pad from feeling cool.