Features: 1.Every product has a unique Manufacturing Part Number label on the inner package that proves it has been qualified,which include Part Number,Model Number and inspection date information;2.If you have any questions about the item,please provide us the Manufacturing Part Number for checking,your profits will be guaranteed.3.Modulus: 0.5M, T: 20T, Protrusion size: 9x7mm/0.35inchx0.28inch (DxH), Aperture: 4mm/0.16inch.4.Made of brass, long time service.5.Shaft Z1=1, shaft turns a circle and drives the gear wheel to turn a T, can get a large transmission ratio, generally in the power transmission, the transmission ratio I=10-80, like big transmission ratio, if use with gear transmission, will need to take the multi-stage transmission.6.The transmission structure of shaft gear wheel is simple, compact, small volume and light weight.Specifications:Modulus: 0.5M 20TMaterial: BrassColor: YellowBrand name: leopardSize:Gear diameter: 11.2mm/0.44inchProtrusion size: 9x7mm/0.35inchx0.28inch (DxH)Aperture: 4mm/0.16inchWeight: 30gPackage include:5 x Brass Gear Wheel 0.5M 20T5 x Screw