The interactive marble run system from Ravensburger. With the GraviTrax marble run system, you can build your own marble run world by creatively using the laws of gravity. Use the various building 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 extensions, it can be expanded for limitless building and playing fun! Add even more speed with the expansion sets. The interactive marble run system from Ravensburger. criss-cross, above and below! A maximum of six routes can cross the Helix. When a marble leaves the block, it rolls on to a lower level without changing direction. This means that a maximum of six marbles can pass the action block simultaneously. Combined with a Starter Set, more complex tracks can be built without the marbles blocking each other on the way to the finish line. With the GraviTrax® marble run system, you can playfully discover gravity, and with various extensions, it can be expanded for limitless building and playing fun! Add even more speed with the expansion sets. Contents: 1 Crossing action block, instructions