The GraviTrax SkyTrax Action Set (Medium, 122 pieces) kicks your marble run builds into high gear with gravity-defying towers, swooping slides, and all-new Skytrax stones that catch, drop, and bridge your marbles mid-air. Whether you're a first-time tinkerer or a seasoned builder, this set brings hands-on thrills, creative engineering, and physics you can actually play with. Compatible with the full GraviTrax universe for endless expansion and experimentation.