Spur Gear, Metric Module Pitch 0.5, Bore Diameter 4 mm, Bore Type Plain, Hub Type Hub with Set Screws, Hub Diameter 8.5 mm, Hub Projection 7 mm, Face Width 3 mm, Pitch Diameter 10 mm, Material Brass, Pressure Angle 20 Degrees , Bore Diameter Tolerance H7, Gear Shape S1, Includes Set Screw.