... ; Vibration level: V1,V2,V3,V45. Innder windage code: C0,C2,C3,C4,C56. Precision Grades: P0,P6,P5,P4,P2 ... , 33000,6000,6200,6300,6400,51100,51200,51300,51400,DAC,BC, etc.Ring MaterialChrome Steel ,Carbon steel,Stainless steelTolerance gradeGB/T307 ...