Connect different levels of your tracks with the “GraviTrax FlexTube” and keep the fun racing along! What comes up, must come down, and with the “GraviTrax FlexTube” you’ll easily change your marble’s direction and track level in a race to the finish! Four FlexTubes are included, and each may be configured in a 60-degree angle, u-shaped or s-shaped tubes to add extra stunts to your amazing marble run. The set also includes 4 height tiles to raise your run even higher! It’s a snap to combine “FlexTube” with any “GraviTrax Starter-Set” to experience the power of gravity and educational fun today! What makes a great toy? GraviTrax checks all the boxes! It’s a creative, modular, expandable track system that challenges children to use their imagination to design and build their own marble runs! Electronic-free, GraviTrax construction sets use STEM-friendly concepts while building critical thinking and problem-solving skills. Completely open-ended, every GraviTrax set has a boredom-busting variety of play options for hours of fascinating fun. Once the basics are mastered, simply add expansion sets and accessories to propel those metal marbles around the tricked-out track of your dreams! Comes complete with 4 FlexTubes, 4 height tiles and instructions.