24-volt heating and air conditioning systems. Low voltage control of gas or oil heating and cooling equipment. Bimetal temperature sensor. Snap acting switch magnetic switch does not require leveling and is mercury-free. Simple worry-free operation. Compatible for heating furnace warm air hot water steam or gravity and gas fireplaces. Features . Economy - Heat and cool only. Dimension - 17.07 x 8.12 x 9.32 in.. Item weight - 0.59 lbs.