The Oternal® Anti-Bark Collar stops barking with progressively increasing beep/sound and vibration which is controlled by a microprocessor distinguishing your dog’s bark from other environmental noises and automatically delivers sound and vibration after each bark, most of the pets will quickly understand the new sensation is telling her to be quiet. It can be adjusted to control the sensitivity, according to the size of dogs barking. This technique of progressively increasing sound and vibration is not only more humane, it is more effective in breaking the barking habit than conventional bark control collars. How to it works: At the first bark, the Collar applies a short warning tone . if a second bark occurs within thirty seconds, a more intense tone is sounded. From the third bark, a more intense tone is sounded along with a short , mild vibration. This pattern is repeated through 7 correction levels. The first two levels are only with progressively warning tone. If your dog continues to bark through the rest five levels, the more intense sound and vibration are applies until your dog stops for thirty seconds, and then it will automatically resets to the first “tone only” level of correction. If the continuous stimulus reaches the 7 levels, then the Collar will stop working for 1 minutes to protect the dog. The use of the warning tone sets up a pattern that your dog will quickly learn is caused by its own barking. It takes time to break bad habits. When your dog forgets and barks again, the warning tone reminds your dog without immediately applying uncomfortable stimulus.