Whenever your dog - or your neighbour' s dog- barks, he will hear a safe, high-pitched sound (inaudible to most humans) that will cue him to stop his annoying habit. Modelled to look like a birdhouse, the bark controller is battery-operated and has three settings plus a test option. Our ultrasonic outdoor bark control unit looks like any ordinary birdhouse that can hang in a tree, on a fence post, or anywhere outside. With a range of 50 feet, the ultrasonic sound could cover a 1/4 acre yard.