Add some surprise to your tracks by sending up to three marbles into the Gravitrax Pro Vertical Mixer and see which sides they exit from Mix up the marbles’ journey with the Mixer. Add some surprise to your tracks by sending up to three marbles into the Mixer and see which sides they exit from. Combine this accessory with the GraviTrax Pro Starter Set. This set includes 1x Mixer BaseThis 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! Are the gravity spheres stopping or flying off before reaching the end target? Time for some problem solving. Rebuild and try something different! The GraviTrax track system can be extended indefinitely with extra track packs and add-on’s – each sold separately. Suitable for ages 8 years and up. Contents: 1x Mixer Base