This double pole 115Volt AC contactor (relay) is found in the control box on all Hot Spring models through the end of 1989. It is used as the Interlock Relay only on the 115v. Hot Spring models. On the 220v Hot Spring models, it is the only relay found in the control box. So it will be used as the Interlock Relay, Jet Pump Relay and Heater Relay.