The BlueSpot Stove Pipe Thermometer monitors flue pipe heat to give an accurate reading on the temperature of the stove. Features a thermal expansion coil on the rear that expands and indicates on the front of the thermometer gauge when to reload your stove to keep it efficient; too low and creosote is building up in your stove pipe and too high and you are losing energy from the stove. Specifically designed to be used with wood-burning stoves. Designed to help save energy wastage and avoid costly flue pipe repairs due to creosote and soot build-up.