With a variety of tiles; levels; tracks and elements; you can control the speed of the marble. The open-play 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 this epic marble run toy. The balls disappear with the tunnel expansion! This set brings the element of surprise to the marble run! Combined with a GraviTrax starter set; there are even more combination and acceleration options.