1 mm, Bore Type Plain, Face Width 5 mm, Gear Shape HA, Hub Diameter 20 mm, Hub Projection 7 mm, Material Aluminum Bronze, Metric Module Pitch 0.Worm Wheel, Bore Diameter 5 mm, Bore Diameter Tolerance +/- 0.5, Number of Starts 1, Number of Teeth 50, Outside Diameter 26 mm, Overall Length 12 mm.