Split the directions of the marbles with the Splitter. See if the marbles have enough speed to roll across the trap door. If they roll too slow, the marbles will fall to awaiting tracks below and will go in different directions. Combine this accessory with any GraviTrax® Starter Set. GraviTrax is a modular interactive track system where you can design and build your own marble runs. This STEM toy for children 8 and up encourages experimenting with gravity, magnetism, and kinetics to propel your marble to the finish. Designed with open play in mind, the concept offers endless possibilities to design a different track every time you play. Expand your builds and add some action with a variety of expansion sets and accessories.