The PetSafe Ultrasonic Bark Control effectively deters barking when it is worn.
When the microphone picks up the sound of your dog’s bark, the unit emits an
ultrasonic tone that can be heard by your dog, but is silent to most humans.
Startled by the high-pitched tone, the dog should stop barking, as it will
associate its bark with this unpleasant noise. For dogs 3.6kg and up, fits necks
up to 71cm, water resistant, batteries included, battery usually lasts 1-3
months, low battery indicator.