Invensys Appliance Controls 275-2720-01 Thermostat, Invensys, 5/16", 60", SPST, 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: 60" Bulb Thickness: 5/16"