Series 210-5 Automatic Gas Shutoff Valves are used in gas water heater applications to protect against overheating water in the domestic hot water supply heating system. It is an immersion-type valve that automatically shuts off the gas supply to the heater if the temperature reaches 210°F (99°C). It is a self-contained device that consists of Buna-N disc-to-metal seating, manual reset button to reopen the valve after an automatic shutoff, trip latch assembly and stainless steel spring seats to close the valve at a controlled temperature, and thermostat with extension tube which operates trip latch in response to water temperature. Design certified by CSA. Models L210-5 M2, LL210-5 M2 and LLL210-5 M2 feature extended shanks for use with water heaters containing extra thick insulation, up to 3 in.