Product description Specifications: Product Name: Gear Model: 11184 and 11181 Materials: Metal Main Gear Size:40x9mm/1.57x0.35Inch(DxH) Diameter of The Main Gear Hole:5mm/0.2Inch Motor Gear Size:14x11mm/0.55x0.43Inch(DxH) Diameter of The Motor Gear Hole:3.175mm/0.13Inch Package Include: 1PC Diff Main Gear (64T),1PC Motor Gear (21T),1 PC Grub Head Screw