Build your own magnetic marble run. This kit comes with different length runs that you can attach to any metallic surface (like your fridge) to create your own unique ball run. Learn about the concepts of flow and gravity as you build and rebuild this never ending marble course. Each set come with 15 runs and four marbles to run down the course you build. Made from quality plastic and magnetic components, you can create and design a run over and over again. Slopes, turns, gravity, heights, and more building a Marble Run from scratch is challenging and teaches the fundamental concepts of engineering in a practical way. This construction toy is great for hand-eye coordination, problem-solving amongst other skills.