Taking design and engineering to the next level. The gears are made with simple ratios (8, 16, and 24 teeth), so lots of other models can be invented. Totally unique D & T product that provides clear links between math and engineering. Lots of new engineering components included. Supplied with work cards and fully tested by schools and experts. Contains 250 pieces. Build 12 different models, 3-4 models can be made at one time.