This Stanley Indoor Electronic Countdown Timer allows you to turn overhead lighting or other devices off automatically. It has intervals of 10, 20, 30 or 60 minutes. It replaces any indoor wall switch and has a hold feature which allows for extended operation. Must be hard wired to existing wall switch wiring and you should consult an electrician when installing. It will help save money and energy – in the OFF position, timer cuts power to device, eliminating wasteful standby power.