needle roller bearing needle bearing roller bearing ISO9001 QUALITY (1)Shield / closure: Open ball bearing, Z, ZZ, RS, 2RS, 2RZ (2)Tolerance code: ABEC-1, ABEC-3, ABEC-5, ABEC-7 (3)Vibration level: V4, V3, V2, V1 (4)Radial play: C0, C2, C3, C4 (5)Material: AISI52100, AISI440C, AISI304, AISI316 (6)Retainer: PTFE, nylon, PEEK or (stainless)steel 2013 hot sale China needle roller bearing NA4900A