GraviTrax Starter SetWith 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. Experience the power of gravity with GraviTrax. GraviTrax Starter Set