Upgraded Version With the latest ultrasonic technology, it is suitable for all breeds and sizes of dogs. The bark control automatically emits high-pitched sounds that only dogs can hear. Automatically sense the sound of the dog, once the dog stops barking, the ultrasonic barking control automatically stops emitting ultrasonic waves. Wide Ultrasonic Range Ultrasonic penetration is 32 feet, covering both indoor and outdoor areas. Compared to 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 32 feet. The smaller the range, the better the effect. The 32-foot wide control range is perfect for stopping your neighbor's dog from barking at you and your family. Safe for Dogs & PeopleUltrasounds do not interfere or harm humans because humans cannot hear these frequency bands, but dogs are sensitive to these ultrasounds. Different dogs may be sensitive to ultrasound in different frequency bands. Please turn the knob to test different frequency bands for best results. If the dog is hard of hearing or aggressive, the device may not work as expected. Use Indoors and Outdoors Humanized bark unit with IP4 rain protection and portable hook for outdoor use, easy to hang on trees, walls or fence posts for dog training in the garden. 2 mounting screws and anchors are included in the package. USB RechargeableThis rechargeable dog bark controller 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, ready to use right out of the box. (It is recommended to fully charge before use, the effect will be better)