Dog Bark Controller

I bought one of these. It works consistently with the dogs that have deeper barks. It does not seem to work as well with dogs who have a higher pitched bark. I have several dogs that live outside. When a chicken or cat walk by, one of them will set to barking which gets all of them barking. This has been helpful in training them not to bark every time something goes by their area. According to the comments, a lot of people are buying these to stop their neighbor's dogs from barking!