UPGRADED DOG TRAINING AND BEHAVIOR AID TOOL: : Adopting the latest ultrasonic technology, the anti barking device will automatically emit a high-pitched tone that only dogs can hear. Automatically sense the dog's sound, once the dog stops barking, the ultrasonic barking controller automatically stops emitting ultrasonic waves. ANTI-BARKING OF ALL SIZES AND BREEDS: : The anti barking device has a choice of 4 sensitivities. The environment can be set up with the best suitable gear, the induction distance can be selected, adjust the sensitivity to achieve. Level 1 is the least sensitive and level 4 is the most sensitive. SAFE FOR DOGS AND HUMANS: : Dog barking control devices with no electric shock, no irritating smell, and no beeping, safe for pets and harmless to humans, the anti barking device will automatically send out ultrasonic waves to stop the dog from barking, perfect for letting you go when you leave your dog The dog keeps quiet and creates a quiet environment for you to your family and neighbors. If the dog is hard of hearing or aggressive, the device may not work as intended. USB RECHARGEABLE DOG BARKING CONTROL DEVICES: : Rechargeable anti barking device with indicator light can be used effortlessly. A 5-hour charge gives you 30 days of use, saving you endless hassle and battery investment. No need to install batteries, it works right out of the box. (It is recommended to fully charge before use, the effect will be better) STOP DOG BARKING INDOORS OUTDOORS: : Anti barking device tested to get the best results within 32 feet, it completely frees your hands compared to traditional dog trainers. You can easily train your dog's behavior by turning on the knob. Great for stopping neighbors and homeless dogs from barking outdoors.