The Thermo Cube is a unique, patented electrical device that plugs into a standard 15 amp electrical outlet and turns power on automatically according to outside air temperature, saving money by using power only when temperatures require heating. There are three models available with different cold temperature ranges to choose from. Each unit has two receptacles for use with more than one electrical dev ice. Cold weather model TC-1 turns on at 0°F, off at 10°F and is ideal for automotive applications, including engine and battery heaters. Cold weather model TC-2 turns on at approximately 20°F, and turns off as temperature rises above 30°F. It is ideal for automotive applications, including engine and battery heaters. Cold weather model TC-3 turns on at 35°F, off at 45°F and is ideal for home and farm applications such as pond de-icers, unheated rooms, pump houses, greenhouses, boats and RV's.