JIS G4805 is standard which specifies the high carbon chromium bearing steels used for roller bearings. It’s similar to ISO 683, DIN 17230, ASTM A295, GB/T 18254 and BS 970 etc.

In JIS G4805 specifications, the bearing steels shall be classified into 5 steel grades: SUJ1, SUJ2, SUJ3, SUJ4, SUJ5.