precision bearing co : 1,ABEC-3,5;Z2V2,Z3V3 2,High speed 3,End cover:ZZ,RS 4,Noise level:Z1, ... bearing is a specialized manufacturer of precision bearing co.Features:1),Shield / closure: Open,Teflon Sealed,Rubber Seals,2 Metal Shield2 ... ),Tolerance codes: ABEC-1, ABEC-3, ABEC-5, ABEC-73),Vibration level codes: V4 ...