Ground Machined Worm Bore Diameter 5 mm Bore Diameter Tolerance +/- 0.1 mm Bore Type Plain Face Width 10 mm Finish Black Oxide Gear Shape W2 Material Carbon Steel Maximum Teeth Hardness 194 HB Metric Module Pitch 0.5 Number of Set Screws 1 Number of Starts 2 Outside Diameter 12 mm Overall Length 18 mm Pitch Diameter 11 mm