This is the device that makes the sound of a ringing telephone louder than a train whistle at 500', insuring that you'll never miss a call. A slider control adjusts the volume of the device's strong electronic ring from 80db to a rousing 95db and its tone can be set to one of three different pitches. The ring sounds continuously for four seconds with a four-second pause between each ring. A bright LED flashes along with the ringer to attract attention visually. The ringer plugs into a modular telephone jack and has a built-in extension jack that allows a telephone to be plugged into it. The compact unit stands on a desktop or mounts to a wall. Plugs into AC. 5" H x 6" W x 4 1/4" D. (1 1/2 lbs.)