Provides coordinated control for heater and filter pump operations * Designed to turn OFF a gas fired swimming pool heater approximately 20 minutes before the filter pump shuts down * Eliminates the problem of pounding and knocking due to overheated water, reduces scale and lime deposits and extends the service life of the heater * The 24-hour dial allows up to 12 ON/OFF operations each day * One set of ON and OFF trippers is supplied with each switch