1. Material: Gcr15 Chrome steel, Stainless steel or Carbon steel;
2. High quality with very smooth feeling, quality standard: ISO9001:2008;
3. Noise level: Z1,Z2,Z3,Z4;
4. Vibration level: V1,V2,V3,V4;
5. Innder windage code: C0,C2,C3,C4,C5
6. Precision Grades: P0,P6,P5,P4,P2(ABEC1,ABEC3,ABEC5,ABEC7,ABEC9)
7. Seal form: OPEN, Z,ZZ,RS,2RS,N,NR