I bought this for my daughter who lives beside 2 large dogs that constantly bark and keep up the entire family all night. First day, we placed it on the outside of the window sill. The dogs came out, barked once, then looked at each other like they were confused and took off running back in the house. It’s been 2 weeks and the dogs have completely stopped. If your trying to stop your neighbors dog from barking, look no further this product will solve your problems as soon as you take it out of the box. We are very impressed!