Put the collar on the dog (collar adjusts from 7 - 27"); Fit the collar snugly around the dog's neck so the sensor and the contacts are able to make good contact with the skin under the dog's fur; Turn the easy turn dial to the needed level (from 1 - 8) or "T" for beeping tone only; NOTE: Stimulation level will depend on size and temperament of the dog; The middle (black) post on the collar senses the vibration from the dog's vocal cords; It WILL NOT activate from loud noises or other dog's barking; The sensor pics up the barking vibration & activates the beeping tone, followed by the Stimulation; This gets the dog's attention, and they begin to associate this Stimulation with their barking so they stop the unwanted barking. Problem solved