This set contains more balls for an even larger fun in ball-track as well as cool storage boxes for already existing GraviTrax balls.The Accessory Ball Box is a must for all GraviTraxers! The four boxes are designed in a cool design of the GraviTrax heights and in the colors green, gray and white. Two of the boxes are already filled with a total of 12 silver and colorful GraviTrax balls, which set the course action in motion. The other two boxes are used as the ideal storage options for existing balls.GraviTrax is a flexible, interactive ball track system for children aged 8 and over: With GraviTrax, children, young people and adults are not only building simple ball tracks. You create unique ball track worlds. By freely designing the ball tracks and exploring the rolling behavior of the balls, the understanding of science is strengthened and gravity can be experienced at first hand. The GraviTrax Universum contains three exciting lines - CORE, PRO and Power. All GraviTrax lines and pr