Notice: This toy is suitable for over 12 years old. The number of packs: 78, the actual type: 71 (because there are 4 tires inside, 2 axles for each, this is for the convenience of DIY production) This is just the accessory we have matched, and it will be ready for everyone to use DIY. But we can't use this to make a car directly. We just provide car accessories. You definitely need to have your own ideas, such as frames, screws and so on. This gear package covers a wide range of spindles, single layers, double layers, crown gears, pulleys, racks, bevel gears, copper gears, bushings, axles, tires, rubber bands and more. The featured gears are: 36MM yellow 2mm hole pulley, rack, four-wheel drive stack, 28-toothed 2mm fan teeth, 30-100mm axle, 30mm outer diameter five wheel wheels The axle length is 30mm, 50mm, 70mm, 100mm, and the shaft diameter is 2mm, two each. Five wheel wheels: 30mm outer diameter, 2mm inner hole, four. Most of the gears are 2mm aperture (tight or loose), except for one 81.5A spindle hole is 1.5mm, there are 2 crowns is 2.5mm, there is 1 crown gear C303A is 3mm, 1 15 teeth 2.3 Mm hole and 3.17mm hole.