【Adjustable frequency technology & 2 in 1】- Dog training device emits the high-stacked ultrasonic sound of different frequencies, which can avoid immune to a certain frequency ultrasonic sound after a long period of adjustment and no longer respond to it, so that you have different sound waves alternately in each time. 【Safe for you and your dogs】 - Unlike other electric shock dog training tools, ultrasonic bark control device uses the latest ultrasonic technology with variable frequencies at 22-25KHZ . The sound does not affect humans, but it can easily attract the dog’s attention and stop their bad behaviors. When your dog is causing mischief, just long press the button (5m range) and point it at the dog. 【Effective Dog Bark Control Device】 - Ultrasonic Bark Control Device provides a safe and effective solution to help owners control unwanted barking and stop some bad behaviors of dogs, like excessive barking, digging, chasing, eating something dirty or fighting, etc. Works well on