1. 2023 Upgraded Dog Bark Deterrent Devices The anti bark device uses the est ultrasonic technology to stop dog excessive barking. It will be triggered by dog bark and start working. Once the dog stops barking, the ultrasonic barking controller automatically stops emitting ultrasonic waves. It uses a way to train your dog to be quiet. 2. Barking Control Devices with 3 Ultrasonic LevelsThe stop barking device has 3 adjustable ultrasonic levels (Audio: 10 16KHZ for small dogs, ultrasonic I: 20KHZ for docile dogs, ultrasonic II: 25KHZ for naughty and large dogs). It's recommended for dogs aged from 6 months to 8 years old. Please try different ultrasonic level bands to obtain the anti bark results. 3. Work Range up to 33ft Barking Control Devices' maximum detect range is 33ft. If the dog is more than 33ft away from the device, it will not be triggered to work by dog bark. It can be used indoors and outdoors, but please make sure there is no obstruction in front of the Dog Bark Deterrent Devices, otherwise, it will affect the anti barking effect. 4. Fast Charge and Long Work TimePlease charge this bark control device before every usage. Use the USB cable to connect the device to a laptop, PC, or charger (output current is no more than 2A). It is fully charged in 5 hours. The dog barking device can continuously work for 30 days after being fully charged. During charging, the red light on means charging, blue light on means fully charged.