The SUPER DOGCHASER uses modern ultrasonic technology to repel dogs. This unit emits a high frequency sound that is in the 20,000 to 25,000Hz range. Humans can't hear this, but dogs can, and they hate it. This device also emits a super bright LED strobing light that confuses the dog and temporarily interferes with its ability to see. Stops the advance of a dog from up to 40 feet away. This device can also be used as a trainig aid and has a special setting for that. You will need one 9 volt battery to power this unit (not included). 4 3/4 inches x 1 3/4 inches x 3/4 inches