This dog barking control collar is great for training purposes. I was hesitant at first to get such an item but then realized that it does not harm the dog in any way. The collar works with vibrations and reacts off the sound vibration of the dog barking. There is no shock, just a vibration that is uncomfortable for the dog. It works very well and leaves our dog uncomfortable enough for him not to bark. The collar is adjustable and fits a small to medium sized dog. It is made very well and looks at though it will last a long time. Hopefully we won't need it too long on him.