The GraviTrax PRO Vertical Expansion Set offers 33 additional elements to reach new heights with your track. Create dynamic marble runs with walls, pillars and balconies that take your tracks to new heights. Whether you create towering three-dimensional structures or suspended tracks, see how high and clever you can build. Combine with the GraviTrax Pro Starter Set and take your track to a new level. This STEM system is an ideal one to teach kids about gravity, magnetism, kinetic energy and fun.