Dual Ultrasonic Transmitters: The ultrasonic anti-bark device includes two powerful sound wave transmitters that can transmit sound waves up to 25 feet, capable of correcting dog's bad behavior and preventing dogs from 'bark. 3. Frequency: PESTON dog bark control device supports stable, fluctuating and irregular sound wave frequencies to prevent dogs from developing specific frequency habits, thus avoiding immunity. Comfortable to hold: The ergonomic body makes it comfortable to hold every time. The ultrasonic barker emits 25kHz ultrasonic waves, which will not affect humans, but can attract the dog's attention without hurting itself. Long battery life: the rechargeable battery 1000mAh battery supports standby up to 30 days and charges in 2-3 hours. Charge using the UPS charging cable included in the box, suitable for computers, laptops, portable power banks, Android devices, and more. How to use: Ultrasonic anti-bark devices are suitable for all types and sizes of dogs aged 6 months to 8 years, except dogs with hearing problems. Package contains: Dog repellent*1