1018 Carbon Steel Ball, Material Carbon Steel, Material Grade 1018, Ball Bearing Grade 500, Ball Weight 2.052 g, Outside Diameter 5/16 in, Rockwell Hardness C60 to C67, Mechanical Finish Polished, Machinability Not Rated, Standards ABMA, ANSI, Outside Diameter Tolerance +/-0.002 in, Brinell Hardness 640, Application Bearings, Industrial, Shape Ball, System of Measurement Inch, Package Quantity 250