To make the bullet train our son a little more interesting, we have bought the bells to disc. The price I think is a little high, but you get quite very good quality. The bells are well finished, the wood is stable, so even small children. The bells have a very nice tone, even the woman at the post office said forward, because the package has been ringing so beautiful when she took it: o) The disc flits not as fast as the bullets, but is certainly a highlight in the ball track.