Stainless Steel Ball 440C Stainless Steel 440C Round Ball Bearing Grade 25 Outside Diameter 1/4 in Outside Diameter Tolerance +/-0.0001 in Fabrication Cold Finished Heat Treatment Through Hardened Heat Treatable Yes Mechanical Finish Polished Not Applicable Brinell Hardness C58 to C65 Rockwell Hardness Includes Material Certificate Yes Standards ANSI/ABMA Minimum Temperature -300 Degrees F Maximum Temperature 1 200 Degrees F Appearance Mirror-Like