shell type needle roller bearings:1,ABEC-3,5;Z2V2,Z3V3 2,High speed 3,End cover:ZZ,RS 4,Noise level:Z1,Z2 ... 5,C2,C0,C3... shell type needle roller ... good at producing K, NA, NKI, NAV, NAOV, RNA series and other series needle roller bearing. And wo also professionally supply all ...