Invensys Spa Mechanical Thermostat 275-3123-00. The bulb is 1/4" thick and has a capillary length of 12".
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
