Designed for residential and small area use. Includes 120V AC adaptor with 30 ft cord. Covers up to 900 sq. ft. Unit switches to battery power during a power failure. The Bird-X Balcony Guard is an effective and ethical solution for repelling pesky birds around the home. Perfect for any deck or patio, this ultrasonic bird-repelling device emits frequencies nearly undetectable to the human ear. Easy-to-install design makes set-up and use easy.