GraviTrax Jr: My Planet Starter SetNow younger kids can enjoy the thrill of watching their ball roll through a fun marble maze they made themselves! GraviTrax Junior is an interactive track system for children ages 3 to 7, with pieces sized for little hands. Easy to assemble with tons of possible track layouts for hours of repeat play! Kids create themed worlds that motivate creative thinking and problem solving. A variety of expansion sets adds to their marble run fun, and its