Dog barking deterrent devices is more effective and human dogs can hear a wider frequency range from 15hz to 120khz this bark control device emits ultrasonic sound at 25khz which is above the hearing range of humans but will easily grab dogs attention and make them feel uncomfortable press the button to stop your dogs bad behaviors like barking digging fighting and more help them understand that their bad behaviors will cause an uncomfortable experience 3 different frequency wave to avoid dogs getting used to simple frequency this ultrasonic dog bark deterrent can emit ultrasonic sounds with 3 different sound waves stable frequency undulating frequency and irregular frequency sound waves you can choose the different waves to void dogs getting used to simple frequency and it can make it reduce the training effect on the simple waves for a long time Recharge dog barking control device with low power light Indicator this sonic bark deterrent usb rechargeable 300mah battery full charge in 1 to 2 hours for about 12 days of regular use saves you the endless hassle and invest in batteries when low power push the function button the indicator will be red