Small and compact in design with an easy buckle collar to fit very small dogs. The DT Bark BOSS bark control collar handles all types of dog barking problems. It features 8 e-stim levels and a beeping warning tone with an easy turn dial. Uses 6V battery (INCLUDED). The collar can be programmed for a beeping Tone only, or a beeping Tone warning with the e-Stim shortly following. Here is how it works: Put the collar on the dog (collar is adjustable from 5 – 28”). Adjust the easy clip buckle collar so that the collar is snug around the dog’s neck. Turn the easy turn dial to the needed level (from 1 – 8) or “T” for beeping tone only. Stimulation level will depend on size and temperament of the dog. (test light included) 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 - only from your dog’s barking. The sensor pics up the barking vibration and activates the beeping tone, followed by the e-Stim This gets the dog’s attention, and they begin to associate this with the barking so they stop the unwanted barking. Problem solved.