It works! They say give it at least 2 to 3 weeks. And big dogs ? are harder to train. Its been less than a week. It has reduced the barking by 80% The older dog has given up and stays on the back porch. The overbred mongoloid is taking longer. He is slowly ? figuring out that the noise stops when he quits. But it takes him 5 to 10 barks. Way better than 100! I’m going to order another one to hit him in stereo.