GraviTrax is the all new STEM track system from Ravensburger Use your imagination to build superb tracks and set the Gravity Spheres rolling More product information Connect between different levels The FlexTube will allow you to easily connect between the different heights in your tracks. What comes up, must come down and with this extension you can easily change the direction of your marbles. The FlexTube can easily be adapted for 60-degree angles, u-shapes and s-shapes. Combined with a Starter Set, the speed in your track can also be controlled. Additional height stones are included in this extension so you can build even higher. How many places on your track can you place the FlexTube? This STEM system [Science, Technology, Engineering and Maths] is an ideal one to teach kids about gravity, magnetism, kinetic energy and fun. Hit a snag? Freestyle with your own track design or use the tasks and blueprints included to help you to get started in the world of GraviTrax Contents This Set includes 4x FlexTubes, 4x Height tiles & InstructionsGraviTrax Flex Tube 26978