Split King (Twin XL) ChiliPad Cube - Single Zone - Heating and Cooling Pad - Fits Your Existing Mattress, Delivers Precise Temperature Control, and Creates the Perfect Sleep Environment WATER BASED COOLING SYSTEM: ChiliPad uses a water-based cooling system that gives you precise temperature control. EXPERIENCE DEEP SLEEP: The ability to regulate your sleep temperature helps you achieve deeper, more restorative sleep. SLEEP TECHNOLOGY: ChiliPad uses innovative sleep technology to create a cooling and heating mattress pad. WIDE TEMPERATURE RANGE: Regulate your sleep temperature from 55F to 110F. SATISFACTION GUARANTEE: If for any reason you arent loving the ChiliPad, contact us and we will get you taken care of.