GraviTrax POWER: Starter & FinishPower up the fun with "GraviTrax POWER Elements Starter and Finish" and automatically send a new ball down the track as each one finishes! Extend your marble run fun and launch a new ball down your track as one finishes handsfree! Ravensburger's "GraviTrax POWER Elements Starter and Finish" links the beginning and end of the track via radio (RF) signal. Load the Starter with up to 7 marbles. As a ball enters the Finish, it signals the Starter to