Covers up to approx. a 300 ft. (+ or -) radius around each unit. Designed for those without electricity. Requires ZERO electrical input to function. Minimal difference in efficiency between the Commercial Ag Unit and the Self-Sufficient Unit except for power source. Approx. 12 inches tall, 7 inches round. Designed to operate outdoors for use in Agriculture and Commercial applications to reduce effects of Stray Voltage, Electrical Pollution, etc.