Specification:Name: Spur Gear Flat GearModel: 1MMaterial: 45# Steel (8 tooth materials is iron)Surface treatment: UntreatedTeeth: eight 12 thirteen 14 15 16 17 18 19 20 TeethProcess Hole: 2.3-12mmPressure Angle: 20°Tooth Surface Hardness: Soft enamel surfaceNote:1.The length of the inner gap could differ because of assorted batches. Please contact us in case you have particular standards for the interior hole size.2.The material of one mod eight tooth is iron, and the material of different enamel is 45# steel, please notice once you purchase.3.The equipment material is product of 45# steel, there could also be rust stains in case of water, which is regular and will not impression usual use.Package :Packing : Plastic bag / Carton box.Quantity : According in your Choose!