Specification: Features: -Work smoothly, structure is firm, and maintenance is simple. -No processing, direct installation, convenient and quick. -For 3mm rod motor shaft - It is made by precision casting. - Spur tools enamel profile. - Standard spur gear. Material: 45# Steel Tooth: 9 Teeth Inner bore:Φ3.12(+0.02/-0.02)mm-------Tight match 3.17mm shaft Outside diameter:Φ7.8mm Thickness :6.3mm Tooth: 12 Teeth Inner Bore: ΦΦ3.12(+0.02/-0.02)mm------Tight match 3.17mm shaft Outside Diameter: Φ8.7mm Thickness: 5.3mm Package: Gear x 1pcs