est Update Version: This dog anti bark device uses the newest 20kHZ-25kHZ variable frequency ultrasound to prevent dogs from barking and correct their bad behavior, the effective range is up to 35ft/10m. Test results and customer feedback show that variable frequency will be most effective for dogs of most breeds and sizes.100% Safe and Harmless: Our dog repeller uses high-pitched ultrasonic sound technology, which will not cause any harm to humans and dogs. But it can easily catch dogs' attention and make dogs stop barking continuously and excessively.1 Button to Stop Dog Barking: The ultrasonic dog repeller is easy to use, you just need to press and hold the button, it will emit ultrasound to attract the dog's attention and prevent your dog or the neighbor's dog from barking, digging without end, when fighting or chewing. Repeated training and appropriate rewards are necessary to achieve the desired result.Rechargeable Battery: Our dog bark deterrents are equipped with a built-in rechargeable lithium battery that supports charging via a faster and more bearable USB cable. 4 Hours fully charged can work 5 months. Green light means fully charged, red light means low battery. Note: The output current does not exceed 2A.Portable Size and After-sales Service: The anti barking device is lightweight and small and can be put in your pocket, it will be more convenient for indoor and outdoor use.