... ball bearing2.Precision level:P0,P6,P5,P43.Seal form:Open,ZZ,ZV,RZ,RS6.Quality standard:ISO9001:2000 & ISO14001 & TS169497 ... ,4. Retainer: copper cage, nylon retainer, steel retainer5. Sealing form: OPEN, Z,ZZ,RS, 2RS china fabric glass ball bearing