Ground Machined Worm Bore Diameter 8 mm Bore Diameter Tolerance +/- 0.2 mm Bore Type Plain Face Width 20 mm Finish Black Oxide Gear Shape W2 Material Carbon Steel Maximum Teeth Hardness 60 HRC Metric Module Pitch 1 Minimum Teeth Hardness 50 HRC Number of Set Screws 1 Number of Starts 1 Outside Diameter 18 mm Overall Length 32 mm Pitch Diameter 16 mm