Science meets creativity with the GraviTrax Bridges Expansion Set. This STEM toy encourages hands-on play where kids lead the way. This 13 piece set has 3 styles of bridges and includes a roll out bridge, narrow bridge and slow bridge. Kids 8 and up can learn how gravity, magnetism, and kinetics propel the marbles through their creations. Designed with modular elements, kids can easily adapt their tracks every time they play. Any GraviTrax Starter Set required.