- 6 Round 'n Round pieces, including 2 Round 'n Round's, increase the fun and overall playability of your existing marble run toy.
- 4 Round 'n Round Topper pieces allow you to increase the stability and complexity of the marble runs you build.
- Standard toy size marbles (5/8 inch or smaller) work with this set (no marbles included with this set).
- Compatible with Marbulous Marble Run Toys, including our Marble Genius Marble Run Super Set (85 pc.), Extreme Set (125 pc.), & Accessory Sets.