Young minds can build ball track structures. This 50 plank set gets children rolling with constructing ‘turbines’, ‘steep curves’ and much more. Then watch the balls race! The 50-Plank Set helps kids get things rolling with two balls and ideas on how to build a “Shooting Gallery,” “Turbine,” “Step Curve” and lots more! This set includes; 50 high precision pine KEVA planks, two KEVA lightweight balls and an instruction booklet. Compatible with KEVA: Contraptions 200