【Adjustable Frequency Technology & 2 In 1 】- POIIOPY dog training device can emit the high-pitched ultrasonic sound of different frequencies, which can avoid becoming immune to a certain frequency ultrasonic sound after a long time of adaptation and no longer respond to it, so you can use different sound waves alternately in each period of time. Use the BEEP MODE before each use of ultrasound mode, so that some dogs can be conditioned to reflect, and they will react after hearing the BEEP sound. 【SAFE TO YOU & YOUR DOGS】 - Unlike other electric shock dog training tools, POIIOPY ultrasonic anti-bark device uses the latest ultrasonic tech with Variable frequencies at 22-25KHZ. The sound does not affect humans, but can easily grab the dog’s attention and stop their bad behaviors. Every time your dog makes mischief, simply LONG press the button (the effective range is 16.4ft / 5m) and point the ultrasonic dog training device directly at the dog. 【EFFECTIVE DOG BARK CONTROL DEVICE】- POIIOPY ultrasonic bark control device provides a safe and effective solution to assist owners in controlling unwanted barking and stop some bad behaviors of dogs, such as excessive barking, digging, chasing, eat something dirty or fighting, etc. Works well on many sizes of dogs (except dogs under 6 months and aggressive dogs).