The interactive ball track system from Ravensburger.

With the GraviTrax Starter Set XXL, the inventive spirit is unleashed and you can dive straight into the huge, endlessly expandable marble run universe. With over 240 parts and a variety of building blocks, nothing stands in the way of surprising and action-packed building fun. The example tracks and instructions provide a playful introduction to the GraviTrax universe and encourage creativity for building your own tracks.

GraviTrax is a flexibly expandable, interactive marble run system for children aged 8 and over: With GraviTrax, children, teenagers and adults don't just build simple marble runs. They create unique marble run worlds. By freely designing the marble runs and exploring the rolling behavior of the balls, the understanding of science is sharpened and gravity can be experienced at first hand. The GraviTrax universe includes three exciting lines - CORE, PRO and POWER. All GraviTrax lines and products can be freely combined with each other. The GraviTrax universe can be expanded infinitely with countless extensions with classic building elements or bricks that enable special action and tricks. So everyone can tinker, try things out and build beyond themselves.