... made of steel, that rotates between two rings with polished raceways. The design of the ball bearing allows ... Z, ZZ, RS, 2RS, 2RZ Ball bearings snap ring: N, NR Tolerance code: ABEC-1, ABEC-3 ... With one or two side metal shields Z and ZZ (2Z) With a snap ring groove in outer ring N With a snap ring ... groove in outer ring and external snap ring NR ...