Ravensburger's interactive marble run system. With the GraviTrax® marble run system, you can build your own marble run world by creatively using the laws of gravity. Use the various construction elements to create an action-packed course and guide the marbles to the finish line using magnetism, kinetics, and gravity. With the GraviTrax® marble run system, you can playfully discover gravity, and with various expansions, it can be extended for limitless building and playing fun! Add even more speed with the expansion sets. Age 8-99 years Packaging 11x11x6cm Requires 2xAAA batteries (not included)