Suitable for all breeds and sizes of dogs, it can effectively block the barking of your dog or your neighbor's house, preventing dogs from barking at specific times, and the ultrasonic barking controller has an effective distance of 25 feet. Outdoor Ultrasonic Barking Control with 3 Adjustable Ultrasonic Range Levels and Test Modes: Low Range, Mid Range, High Range, Test Mode (for verifying microphone and speaker functionality) Ultrasonic frequencies are not harmful to pets, humans Completely inaudible to the ears. It provides a safe and effective training tool for your dog or your neighbor's dog to stop barking. Suitable for most dogs in this range. The anti-bark device is durable and waterproof. It can be hung on a tree, wall or fence to keep your own dog or your neighbor's dog from barking, and it can be used both indoors and out. The new dog bark controller features a well-designed mini shape that is easy to place and hide. The bi-color indicator shows whether the battery is sufficient. When the external bark control is within range of the dog barking, the microphone picks up the sound and automatically activates the device. The external anti-indentation controller emits ultrasonic waves. (Ultrasonic noise can come from dogs, but is muted for humans)