Expand your gravitrax starter-set with the tram expansion pack. With this set, you can take your gravitrax system to a whole new level. Combine the vertical blocks, curves and tracks with your gravitrax starter set for even more action and suspense. How long can you keep the marbles going? Can you beat your own record? With the gravitrax interactive track system, You can design and build your own race tracks and experiment with gravity, magnetism, and kinetics to propel your ball to the finish. With a variety of tiles, levels, tracks and features, you can control the speed of each ball. The open-ended building concept offers endless possibilities to design a different track every time you play. Add flair and speed to your tracks with expansion sets and action accessories. Experience the power of gravity with gravitrax.