Humanized Design & Portable SizeWhen you press the button, the dog anti bark devices can emit ultrasonic sound to attract dog's attention and prevent excessive barking. The LED light on the top of the button can indicate working status or low battery. Small size and anti-static wrist strap allow you to take it wherever you need. Improves the effectiveness of dog training: The ultrasonic deterrent combines training and bark control, which can Train your dog to stop unnecessary behaviors, barking, digging, eating dirty things or fighting for effective and lasting results with continued training. Suitable Occasions: Bark control devices are used to prevent barking your dog's useless indoors, to train those adventurous puppies indoors, to walk dogs outdoors and to train them to show good behavior in public and avoid fighting and eating dangerous foods . Adjustable Frequency DesignThis bark control device has extra "ultrasonic frequency conversion" function than similar products, which makes i can prevent dogs from showing resistance to fixed frequency ultrasonic waves, so as to prolong the effective training time. him, or switch to variable frequency ("II") when the dog does not respond. Once the dog reacts positively, please praise and reward him to strengthen his memory.