52100 Alloy Steel Ball Material Alloy Steel Material Grade 52100 Ball Bearing Grade 25 Ball Weight 0.266 g Outside Diameter 4 mm Rockwell Hardness C60 to C67 Mechanical Finish Polished Machinability Not Rated Standards AISI E52100 Outside Diameter Tolerance +/-0.00254 mm Brinell Hardness 654 Application Aerospace Automotive Clean Energy Factory Automation Material Handling Medical Packaging Printing Heat Treatable Yes Heat Treatment Tempered Shape Ball