The Animal Chaser keeps unwelcome guests from your property. When an animal enters the large area covered by the infrared sensor, the Animal Chaser produces a sound that is very unpleasant to cats, dogs, and even racoons but inaudible to the human ear. The unit switches off automatically when the animal has left the area for extended battery life. Effective up to 40 feet, Weather resistant, Built-in test button and LED indicator.