Ground Machined Worm Bore Diameter 15 mm Bore Diameter Tolerance +/- 0.2 mm Bore Type Plain Face Width 45 mm Finish Black Oxide Gear Shape W3 Hub Diameter 30 mm Hub Projection 17 mm Material Carbon Steel Maximum Teeth Hardness 60 HRC Metric Module Pitch 2.5 Minimum Teeth Hardness 50 HRC Number of Starts 1 Outside Diameter 42 mm Overall Length 65 mm Pitch Diameter 37 mm