Adjustable Sensitivity & Frequency - The anti barking device has 4 levels of sensitivity and 4 levels of frequency (15KHZ-30KHZ) adjustable. Different dogs may be sensitive to ultrasound in different frequency bands. Please turn the knob to test different frequency bands for best results. The dog device is suitable for dogs between 6 months and 8 years of age, except for dogs with hearing impairments or under 6 months and special large dogs. Safe for Dogs and People - The Bark Control uses ultrasonic technology to allow humans to hear slight sounds but not affected by the sound, but dogs will be sensitive to these ultrasonic waves and other family members or neighbors will not worry about being affected. Ultrasounds do not inflict substantial penalties on dogs. Different dogs may be sensitive to ultrasound in different frequency bands. Please turn the knob to test different frequency bands for best results. Easy to Use - The bark control device use the latest ultrasonic technology, suitable for all breeds and sizes of dogs. The device has a built-in pickup that can detect the dog's barking within 50 feet and automatically emits ultrasonic that the dog can hear. Once the dog stops barking, the device automatically stops. Effectively training your dog to stop excessive and noisy barking. USB Charging and Waterproof - Bark controller has IP4 level waterproof, the case is UV resistant and not easy to fade. It can be easily hung on a tree, indoor, outdoor wall or fence to stop any dog barking. And it uses USB charging, it can last at least a week on a single charge, no need to buy batteries frequently, saving you money. Great Rang 50FT - The ultrasonic penetration range is 50ft, covering indoor and outdoor areas. Compared with traditional dog trainers, it completely frees your hands. You can easily train your dog's behavior by turning on the knob. Tested for best results within 30 feet. The smaller the range, the better the effect. If you or your neighbor's dog barks too excitedly, put it in the right spot and you'll have a quiet resting environment.