small shaft bearings:1,ABEC-3,5;Z2V2,Z3V3 2,High speed 3,End cover:ZZ,RS 4,Noise level:Z1, ... the following types, Metal Shield Bearings Open Bearings Rubber Seals Bearings Teflon Sealed Bearings Flanged Ball Bearings Thrust Ball Bearings Hybrid Ceramic Bearings Hybrid Ceramic Bearings High Performance small shaft bearings