Used to control THERMOWELL heating mantles or other resistive heating circuits (hot plates, heat tapes, water baths, etc). Offers a wider range of control than proportional on/off type. It may also be used to control incandescent lamps, room fans, stirring motors. 60 Hz. Model SS-4: A cast aluminum case with gray, baked-on finish, satin SS face plate with flush-mounted receptacle and dial plate, pilot lamp and a 3 ft, 3-wire power cord with U.S. plug.