The safe, effective way to stop excessive barking. Self-adjusting unit delivers immediate, effective stimulation only when your dog barks. The more he barks, the higher the stimulation. As he learns, the intensity of the stimulation decreases.No external programming or controls. Just place it on your pet and it's ready to go to work helping your dog control his unwanted barking. Activated by vibrations from your dog's vocal cords, this unit delivers stimulation only when your dog barks and is not activated by other sounds or the barking of other dogs.Kit includes lightweight receiver, nylon collar, short and long probe contacts for varying coat lengths, battery charger, receptacle covers, training video, and instructions.