In combination with the electronic GraviTrax Power Element Trigger and another Power Element, the track is influenced. The bricks communicate with each other through invisible connections. One track, countless possibilities! The course of the balls is controlled by skilfully installing the electronic GraviTrax Power Elements. The trigger can be used in combination with other power bricks, such as the Switch, Starter or Lever, to create invisible connections. (Not included in the product). These represent three colour channels: Red, Green or Blue. For even more action, much longer running times and more complex track construction. The electronic GraviTrax Power Element Trigger in combination with another power brick influences the course of the track by means of a wireless connection. These represent three colour channels: Red, Green or Blue. For even more action, much longer running times and more complex track construction. 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 behaviour of the marbles, the understanding of science is sharpened and gravity can be experienced at first hand. The Stem symbol on Ravensburger products signals a category of games that make science a playful experience. Stem (Science, Technology, Engineering, Mathematics) corresponds to the German MINT (Mathematik, Informatik, Naturwissenschaft, Technik). Children can use various extensions to enlarge their marble runs and design them again and again. Contents: 1 power trigger; 1 instruction booklet, 1 warning booklet.