1) Designed by sound control and fitted on the wall. 2) When the dog barks, the sound arouse electric circuit. Ultrasonic wave will emit from product, it discomforts dog but has no harm to dog. Such ultrasonic wave is heard by dog but not by people. 3) After several repeated action, the dog know the extra sound has been caused by his bark , so establish a conditioned reflex. Afterward he would not bark without reason 4) Adapt integrated circuit, when continuous 3 barks will arouse circuit, but one bark or sudden sounds from environment could not cause unit emitting ultrasonic wave. 5) Bark loud level, different distance away from unit, noise of environment can affect unit working correctly. 6) So it's not certain that continuous 3 barks can intrigue unit, but its effect is available. 7) Material: ABS 8) Power: 2W 9) Rate Voltage: 8.4W 10) Power supply: DC 8.4V / 500mA 11) Input voltage: AC 100~240V 12) Work frequency: 25KHz 13) Can generate 2 x 128dB strong ultrasonic 14) Effective