52100 Alloy Steel Ball Material Alloy Steel Material Grade 52100 Ball Bearing Grade 25 Ball Weight 1.05 g Outside Diameter 1/4 in Rockwell Hardness C60 to C67 Mechanical Finish Polished Machinability Not Rated Standards AISI E52100 Outside Diameter Tolerance +/-0.0001 in Brinell Hardness 654 Application Automotive Heat Treatable Yes Heat Treatment Tempered Shape Ball System of Measurement Inch Package Quantity 100