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The accuracy of YJ deep groove ball bearings is divided into four grades of tolerances with National Standard of P.R. of China : GB/T307. 1-94 which comparisom whih the ISO-standard,ets is im the following table.

standard	Tolerance class
YJ (GB/T307.1-94)	P0	P6	P5	P4
ISO492	Normall class	class6	class5	class4
AFBMA STD.20-1987	ABEC-1	ABEC-3	ABEC-5	ABEC-7