This device mounts over any toggle wall switch and automatically turns it on and off without requiring any hard wiring. You can set the device to flip the switch up to nine times a day and remain on for one minute to 24 hours. As easy as setting an alarm clock, the unit's LCD control panel allows you to quickly choose the exact minute you want the switch to turn on a light or ceiling fan. Requiring no more space than the switch plate itself, the timer simply screws into the bottom hole of the face plate and still allows you to turn the switch on or off with the touch of a button regardless of the programmed time. Includes mounting screw. Requires two AA batteries. 5" L x 3" W x 1 3/4" D. (5 oz.)