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 W1 Hub Diameter 30 mm Hub Projection 18 mm Material Carbon Steel Maximum Teeth Hardness 194 HB Metric Module Pitch 2.5 Number of Starts 1 Outside Diameter 42 mm Overall Length 63 mm Pitch Diameter 37 mm