Additional set for the constructor - GraviTrax Start&Finish

GraviTrax - experience the power of gravity! GraviTrax — it is an interactive marble tracking system that you can design and build yourself, experimenting with gravity and exploring the laws of physics.
The GraviTrax Power Starter & Finish extension is used for the automatic release of... marbles. The elements interact automatically — the Finish sends a signal that makes the starter release another ball onto the track.