This phone flasher with a 180-degree dome cover and a 10Cd ultra-bright LED to guarantee you will not miss any call. Can be used anywhere in any phone system, video phone system and some PBX systems. Just unplug your phone from the wall jack, plug the phone flasher into the wall jack and then plug your phone into the phone flasher. It's that easy. No batteries needed. Includes a double-sided sticky-pad so you can secure the strobe to a wall or table surface. One year warranty.