Product Information:This Time Switch provides coordinated control for heater and filter pump operations. This two circuit switch is 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 ONOFF operations each day. One set of "ON" and "OFF" trippers supplied with each switch. Minimum ONOFF time is one hour. Features:#149; Provides Automated Control for Heater and Filter Pump Operations#149; Two Circuit Switch is Designed to Turn Off a Gas Fired Swimming Pool Heater Approximately 20 Minutes before the Filter Pump Shuts Down Specifications:#149; Switch Rating: 40 Amp resistive, 125 Volt, SPST Switch #149; NEMA 3R Case Dimensions: 93/8" H x 51/2" W x 35/8" L #149; Knockouts: Combination 1/2" 3/4" nominal knockouts, one on the back and each side of case, two on bottom