Build the ultimate ball track with SmartMax Mega Ball Run set that contains an amazing 71 pieces! With endless options you can make all kinds of crazy and fun structures and watch the balls roll down. This set contains special parts including tubes and X-shaped bars with 4 magnetic ends for extra building fun. All the pieces are large so that they cannot be swallowed. Compatible with all other SmartMax sets this STEM magnetic construction set is perfect for being creative and developing STEM skills.