Invensys Appliance Controls 275-3317-02 Thermostat,Invensys,Patrol/Aquaset,5/16",48",SPDT,25AThermostats Single pole rated at 25 amps with max temp rating at 107°F. Best results are obtained when the bulb is installed in a dry well or groove tube at or immediately before the heater. This is a safety device! If it is found to be out of calibration, do not attempt to perform a field adjustment! Replace bad thermostat with a new one Capillary Length: 48" Bulb Thickness: 5/16"