This is a great alternative to the shock collars that are used for trainnig. This one first gives out a warning beep and then vibrates. It startles them not hurts them. It is on an adjustable collar made to fit medium or small dogs. There are 2 bone face plates so you can pick orange or blue. The battery compartment is behind the faceplate and behind the collar. They sent 2 batteries. It also comes wit ha wrench to switch out the vibration nubbs on the back of the collar for medium or small dogs. #Rankboosterreview #Sponsored #BoscoKnows https://www.amazon.com/Barking-Training-Dogs-Stop-Vibration-Technology/dp/B075Z1GS9Z