Toys that Teach: Explore engineering and creativity with open-ended marble mazes. The cubes’ multiple exits give your own designs multiple pathways. Test probability and basic physics when you let the marbles loose! Play Sized: Rails Extreme has 82 cubes and 18 rails! It’s the ideal size for any long rainy day of experimenting with racing rails and even more possible paths for your marbles. Rails Set: The Q-BA-MAZE Rails Extreme gives you rails and coaster tubes for new exciting runs! You can even build shapes with incredible zig-zags and shortcuts. All Q-BA-MAZE 2.0 sets are compatible. Precise Engineering: MindWare Q-BA-MAZE 2.0 cubes are made for precise marble action. Snuggly-fitting connectors stack directly on top of each other or use side connectors to create diagonals and shapes. Includes: 82 cubes, 18 straight-away rails, 4 marble catchers, 4 coaster tubes, plus 20 steel marbles (not magnets) and 1 design ideas booklet.