GraviTrax PRO Add on SplitterThe GraviTrax PRO Add on Splitter Expansion is an expansion item that can be combined with the GraviTrax Starter and Pro Set. 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 the GraviTrax Pro Starter Set. This set includes 1x Splitter Base