Quiet, effective ultrasonic bird control, outdoors. This is the world's first ultrasonic (silent-to-humans) repeller designed for use outdoors in semi-enclosed spaces. 4-speaker system covers up to 3,600 sq. ft. Irritating, alarming ultrasonic noises intimidate birds to leave State-of-the-art technology decoded, customer support available Ideal for gas stations, parking lots, warehouses, patios, etc.