What is Gravitrax? Design! Follow the plans or challenge yourself by designing your own marble run racing system. Build! With over 100 pieces 18 unique action parts, the Starter-Set gets you launched! Expand! Add Expansion Sets and Action Accessories for infinite possibilities! Race! gravity determines each ball's destiny -- but you have the power to change it! Learn! Fun science and engineering concepts like gravity, magnetism, and kinetics make STEM exciting! For Ages 8 Product video available! The Gravitrax App Added Bonus! Download the free App for your smartphone or tablet, build your own marble run system and play with different marbles and camera perspectives from the ball's point of view! Test new layouts in the app and then build them in real life with your Gravitrax system. We even added Virtual Reality features (compatible smartphone and VR headset needed).