Dog Ultrasonic Anti Barking Control Device Deterrent Training Device setProduct features: 1. An ultrasonic anti barking device can automatically detect dog barks 50 feet away. The barking control device automatically emits high sounds that only dogs can hear. After the dog stops barking, the ultrasonic barking control will automatically stop emitting an ultrasound. 2. Ultrasound is harmless to pets and completely inaudible to human ears, so the device can be used safely 3. Can be hung on a tree, indoor, or outdoor wall,