It is called a Jolly Ball and it is made from hard plastic so there is no getting hold of it in his mouth. It is a thing with the herding breeds and I have heard there is actually a sport in some places. He has always just went pretty much insane with that thing, barking extremely loud nonstop at it for hours if I don't take it away from him. That is hard to do as he will not give it up! Have to trick him..