Description: If you are a model amateur, you would know that gears are essential and necessary parts for models. Aircraft, automobiles, boats, robots and other small production of science and technology will all need to use gears. Here we provide 19pcs gears of different sizes which may meet your basic needs for model making. They are also good replacement parts of old or broken gears. Features: Made of high quality plastic, wearable and long service life. The products are for toys gear spare parts, suitable for DIY model technology production. Small parts, easy to use, great model making accessories for all kinds of cars, robots, etc. This is the gear set including 19 kinds of gear parts. It can meet your DIY needs. 16102B for example means 16 outer teeth, 10 inner teeth, aperture diameter is about 2mm and loose-fitting 2mm shaft. Specifications: Material: Plastic Color: White Modulus: 0.5 Thickness: 4~5mm Type: 16102B, 18102A, 20082B, 20102B, 22082A, 22102B, 24102B, 24122B, 26082B, 28102B, 30122B, 30162A, 32082B, 34102B, 38082B, 40102B, 46082A, 48102B, 50102A 1. The first and second number is outer teeth number 2. The third and fourth number is inner teeth number 3. The fifth number is aperture diameter 4. 2A means center shaft is 1.95mm and close-fitting with 2mm shaft. 2B means center shaft is 2.05mm and loose-fitting with 2mm shaft. 5. Gear outer diameter=(teeth number+2) x 0.5mm e.g. 16102B means 16 outer teeth, 10 inner teeth, aperture diameter is about 2mm and loose-fitting 2mm shaft. Gear outer diameter =(16+2) x 0.5mm=9mm. Weight: 9g(approx.) Package Includes: 19pcs x Gears