Dual Ultrasonic Transmitters: Equipped with two powerful sonic transmitters with sound waves up to 25 feet away, PESTON Ultrasonic Dog Bark Deterrent is able to correct unwanted dog behavior and stop dog barking. 3 Frequencies: PESTON Dog barking control devices supports stable, fluctuating and irregular frequencies of sound waves to prevent dogs from forming a habit of a certain frequency, thereby avoiding immunity. Comfortable Grip: The ergonomically designed body makes every grip comfortable. Ultrasonic barking emits 25 kHz ultrasonic waves, which will not affect humans but can grab dogs’ attention with no hurting. Long battery life: 800mah rechargeable battery supports a standby up to 30 days for 2-3 hours of charging. Recharges with a UPS charging cable included in the box, which works with computers, laptops, portable power banks, Android devices, etc. Instructions: The anti barking device for dogs of all types and sizes from 6 months to 8 years old, excluding dogs with hearing problems.