Obi has a collar but I only put it on him when I let him outside (weekends, when I'm around to monitor him). It's one of the break-away collars. I bought two, actually, to see how effective the break-away thing is and it worked when I hung something from it (approx 10 lbs). I took the bell off. Obi never messes with it, and doesn't seem to mind at all. In fact, he gets excited when I bring it out, because he knows that it means outside time has come!!