Worm Wheel Bore Diameter 4 mm Bore Diameter Tolerance +/- 0.1 mm Bore Type Plain Face Width 5 mm Gear Shape HAT Hub Diameter 9 mm Hub Projection 7 mm Material Bronze Metric Module Pitch 0.5 Number of Set Screws 1 Number of Starts 1 Number of Teeth 20 Outside Diameter 11 mm Overall Length 12 mm