This control thermostat thermistor sensor detects the spa waters temperature and relays that information back to the system. It simply screws into the No Fault Heater Housing (hand tight only) and plugs into the side of the spas control box. This item is found on the 1995-2000 Hot Spring Classic, 1995-2002 Hot Spring Grandee, Jetsetter, Landmark, Prodigy and Sovereign. It was also used on the 1995-1996 Highlife, 2002 Sovereign ILE (Special Edition) and 2000-2002 Hot Spring Vanguard. This thermistor also found on the Tiger River 1995-1996 Khyber, Manora and Tondi and the 1997-2002 Siberian, Bengal and Sumatran spas.