Dog Repeller, Stops Dogs from Approaching and Barking This Ultrasonic Dog Repeller usually gets an immediate response from most dogs. You can get them to stop their approach or stop them from barking just point the unit directly at them and press the button. Repeat if necessary. Most effecive range is about 6 feet, but may be effective up to 20 feet. Can be used as a trainer (even on your neighbor's dog). Can be used to help emphasize commands like Heel, Sit, Quiet, or Stay. Dimensions, only 4.25 inches long and 1.75 inches wide. Takes one 9 volt battery.