Ultrasonic Dog Bark Control Device, Outdoor Bark Control, Dog Bark Control, Sonic Bark Control, Silent Barking Stop. Features: Ultrasonic bark control devices automatically detect barking when and how far it can go. about 15m/50ft away. The bark control device automatically emits high-pitched sounds that only dogs can hear. Once the dog stops barking, the ultrasonic bark control will automatically stop emitting ultrasonic sounds. Ultrasonic frequencies are harmless to pets and completely inaudible to the human ear, so you can use this device safely. < p> It can be hung on a tree, indoor or outdoor wall or fence post to deter dogs from barking (within reach). When the luxury outdoor ultrasonic alarm clock detects excessive barking, the microphone responds to the barking and echoes the activation. 9V batteries are required (batteries are not included). The outdoor ultrasonic barking device has a power indicator. When you go out, it can be turned off to save battery. Designed for outdoor