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 or cooling. There are five models available with different temperature ranges to choose from. Each unit has two receptacles for use with more than one electrical device. 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. One year limited warranty.