Features: There are 3 pieces planetary gears in the package. Hole diameter: apporx 8mm/0.3inches, thickness: approx 11mm/0.4inches. high quality plastic, Great & sturdy, long for time service. 36 Teeth E-bike Wheel Hub Motor Planetary Gears with Bearing For Ba-fang Motor. Electric bike motor gear, nylon teeth planetary gear, suitable for Ba-fang motor. Specifications: Material: plastic Diameter: approx 38mm/1.5in Hole dia: apporx 8mm/0.3in Thickness: approx 11mm/0.4in Note: Please allow 1-3cm error due to manual measurement. pls make sure you do not mind before you bid. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Package includes: 3x Planetary Gear