The Yard Gard LF emits a high frequency sonic tone that irritates pest animals, forcing them to leave the affected area. The frequency is high enough to be undetectable to most humans, and is user selectable between 15 kHz and 19 kHz at a volume of 90 dB @ 3 feet (most adults can only detect sounds up to 12kHz). It has a range of 4,000 square feet and is effective against a wide range of animals including rodents, squirrels, cats, raccoons, bats, deer and more. When not set to "Constant" the Yard Gard has a built-in infrared motion detector which activates the unit when pests move into the coverage zone (roughly 35' wide x 70' deep). The water and weather-resistant unit comes with a 30' 120v outdoor-rated power cord and also can run off 4 "C" batteries.