Easy Operation Barking Trainer The Bark Stopper uses the newest ultrasonic technology which is safe and effective for stop dog barking, suitable for dogs of all breeds and sizes. Only needs to press the button to activate the sonic and release the button to stop. Human can only hear a beep sound to indicate the working status. Consistent training is required to achieve effective and long-lasting results. Two Modes & Effective in 16.4ftThe two modes with variable frequency and fixed frequency are available in the range of 16.4ft, covering the area indoor and outdoor. The smaller the range, the better the effect. Portable design with a wrist rope for convenient use indoor and outdoor use. Press the button, it will emit ultrasonic sound and the green light indicating that the device is working, the red light indicates low battery status. Multi-purpose Dog Training Device handheld dog training tool is harmless and humane to keep your dog and your neighbors dog from barking. It can also be used as a dog training tool to correct our own dog's misbehavior like excessive endless barking, eating unsafe food, fighting, digging and stop others' dog aggressive or unsafe actions to protect ourselves.