My border collie never tires from chasing the ball usually my arm would but no longer is that the case. This chuck it thrower is a modern day atl-atl created by native Americans for hunting boars and now helps me throw a tennis ball. It's great that it works on regular sized tennis balls or medium sized chuckit balls (I have the orange ball that came with and the glow in the dark ball that whistles). Needless to say my border collie gets tired before I ever do now. Never knew that was possible.