Dog Bark Control & Training:The anti-bark device uses the latest ultrasonic technology which is suitable for dogs of all breeds and all sizes. Stop excessive, noisy dog barking by emitting an ultrasonic sound to silence the dog. After the dog stops barking, the ultrasonic barking control device automatically stops emitting ultrasonic waves. Give you a silent life! 3 Levels of Operation:The anti-barking device with 3 adjustable ultrasonic volume levels -low, medium, and high, 15KHZ-30KHZ applies to large, naughty dogs. 20KHZ applies to the docile dog. 30KHZ applies to small dogs. It's recommended for dogs aged from 6 months to 8 years old. Please turn the knob to test different frequency bands to obtain the best results. because different levels of ultrasonic will have different affections Safe for Dogs & Human:Most humane way to keep your dog from barking. The ultrasound will not cause interference or harm to humans, because humans cannot hear these frequency bands, but dogs will be sensitive to these ultrasounds. However, some dogs may be afraid or dislike this sound and will not stop barking at first, so please allow up to 2 weeks for training. Design & Waterproof:The device is designed for easy hanging or mounting on a tree, wall, or fence post to keep your dog or your neighbors' dog from barking, Our anti-barking device is waterproof and durable, it can withstand any weather conditions; making it an excellent outdoor bark control for dogs. the shell is IP4 waterproof grade, and can effectively resist external splash. But if it rains, it's best to take it back, which helps protect the equipment and extends its life. Fits for Most Dogs: The device works on most breeds and sizes, but does not work on deaf or hearing-impaired dogs. Some dogs may be afraid or dislike the ultrasonic sound, and not stop barking at the beginning. Please allow up to 2 weeks for training.