From the Manufacturer These energy saving timers use no electricity to operate. These timers are designed to replace any standard wall switch, single or multi-gang, and automatically limit the "ON" time of fans, lights, motors, heaters and other energy consuming loads. Supplied with a molded white time dial plate designed to fit either toggle or decorator style switch plates; single or multi-gang with no field modifications required to fit either style switch plate. Time saving "up front" terminal connection with teeter type terminals and an easy "press-on" knob design ensure quick and easy installation.