【Automatic Anti-Bark Dog Device】The device intelligently detects your dog's barking from up to 15 meters away and automatically emits an ultrasonic sound that distracts your dog to stop barking, allowing you to enjoy a moment of peace and quiet. 【Anti-Bark Dog Device】The ultrasonic frequencies are harmless to animals and completely inaudible to the human ear. If the dog is hard of hearing or aggressive, the device may not work properly. It is not recommended to use the same device against two or more dogs that bark at the same time. 【3 Working Levels】This anti-barking device with adjustable frequency is suitable for different types of dogs. The frequency from 15 kHz to 30 kHz is suitable for large aggressive dogs. The frequency of 20 kHz is suitable for gentle dogs. The frequency of 30 kHz is suitable for small dogs. It is recommended for dogs aged 6 months to 8 years. 【USB Rechargeable】This ultrasonic dog repellent has a built-in rechargeable lithium battery, which can work