Dog Ultrasonic Anti Bark Device - Rechargeable Bark Control Unit - Dog Barking Deterrent Unit - Dog Behavior Training Tool Control Unit 16.4ft Effective Control Range with dog whistle This product adopts ultrasonic bark control technology. The product will automatically emit ultrasonic waves after detecting dog barking, which can only be heard by dogs, but not by humans. Dogs are startled by sudden high frequency sounds and usually stop barking. It associates barking with an unpleasant sound, and when repeated several times, the dog will find that the barking causes him discomfort and will reduce barking gradually. This anti-barking method is safe and effective. In order to prevent dogs from sound interference, multi-sound wave processing is technically carried out, so that the device has a continuous effect on the dog’s barking ! Product Name: Dog Repellent