Bearing tolerance class

Precision grade defining tolerances for bore diameter, outer diameter, width and running accuracy of a bearing. ISO/DIN classes: Normal (P0, widest tolerance, 95% of applications), P6 (50% tighter), P5 (75% tighter, machine tools), P4 (very precise, spindles), P2 (maximum precision, instruments). ISO 492 and ISO 199 standards. Brands: SKF, FAG, NSK, GMN (specialty in P2/P4).