The bearings tolerance or dimension accuracy are regulated by "ISO492" standard with:0 Grade;6 Grade ,5 Grade,4 Grade,2 Grade.Class 0 corresponds to normal precision class bearings, and precision becomes progressively higher as the class number becomes smaller; i.e., Class 6 is less precise than Class 5, which is less precise than Class 4, and so on.
The Interchange Table Of Bearings Tolerance Of National Standards Unit：UM
Tolerance For Radial Bearings Except Tapered Roller Bearings Inner Ring
Tolerance For Radial Bearings Except Tapered Roller Bearings Outer Ring Unit：UM
