This 3/4 inch lead freeautomatic gas shutoff valve is used in gas water heater applications to protect against overheating the water in the domestic hot water supply heating system. It is a self contained device consisting of disc-to-metal seating, manual reset button, trip latch assembly, stainless steel spring seats, thermostat with extension tube and extended shank for up to 2 inch thick insulation. This immersion-type valve automatically shuts off the gas supply to the heater if the temperature reaches 210 degrees F (99 degrees C).