a.o. smith by honeywell gas control valve 100262939 2" cavity natural thermostat compatible with a.o. smith, state, american, whirlpool, and craftmaster brand water heaters variety home supply please feel free to contact us directly to determine if this is the correct gas valve for your water heater!!! we will need the model and serial number of the water heater to cross reference properly. the electronic gas control valve incorporates an led status indicator that monitors system operation and service diagnostics. gas control located within hot water heater uses a thermopile to generate the power needed to operate the electronic gas control without requiring an external power source. this product has been certified by a third party to be compliant with the “safe drinking water act” requirements for low lead in potable (human consumption - drinking and cooking) and non-potable water applications (non-human consumption). thermostat is compatible with all a.o. smith branded heaters including a.o. smith, state water heaters, american water heater, whirlpool, craftmaster and reliance. product manufactured by honeywell for a.o. smith. honeywell model # wv8840b1158. please be aware part may come labeled resideo as there was a corporate acquisition. it is still the correct honeywell part!