... level:Z1,Z2,Z3,Z4 Stainless steel miniature deep groove ball bearings1.Model:Open,Z,2Z,RS,2RS,RZ,2RZ2.Quality level:Reach the same level ... Z2,Z3,Z4Vibration level:V1,V2,V3,V4Hardness of the bearing:HRC59-6ApplicationAutomotive,Office equipment,Electric applicance,Electronics equipment,Optical ... United,Realistic,Pioneering and Innovative5.Welcome to inquiry . Stainless steel deep groove ball bearing