Automatic Anti Dog BarkingThe device intelligently captures dog barking up to a distance of 15 meters, and automatically emits an ultrasonic sound that distracts your dog to stop unwanted barking, allowing you to enjoy a moment of peace and silence. Dog Bark StopperUltrasonic frequencies are harmless to pets and completely inaudible to the human ear. If the dog is hard of hearing or aggressive, the device may not work as intended. It is not recommended to use a device against two or more dogs barking at the same time. 3 Operating LevelsThe adjustable frequency dog bark deterrent device is suitable for different dogs. 15KHZ-30KHZ is suitable for large naughty dogs. 20KHZ Suitable for gentle dogs. 30KHZ Suitable for small dogs. It is recommended for ...