Students become mechanical engineers as they build structures with this comprehensive set. Discover how a gear box works, what a planetary gear is and how it works, how a windshield wiper moves, how to design a stable bridge and much more. Enough components are supplied to build 30 models of gears, cranks, wipers, bridges, vehicles, scales and stands. Includes a 134-page full color instruction manual with background information and teaching suggestions. A 9-V battery is required and available separately.