Race up to 6 marbles at once with the “GraviTrax Balls & Spinner”! A quick turn sends the marbles down your amazing marble run in a race to the finish. Since all sets are open-ended, it’s a snap to combine accessories like the “Spinner” with any “GraviTrax Starter-Set” to create unique action in your marble runs. Combine with the launcher (included in the “Starter-Set”) to race up to 9 different tracks at once! Experience the power of gravity and educational fun today!