... authentication ISO9001:2000 4.Hardness:62-65 high quality Taper Roller Bearings Greese/OilAs you requirement, such as SRL ,PS2, Alvania R12 ... ,6200,6300,6400,51100,51200,51300,51400,DAC,BC, etc. Ring MaterialChrome Steel ,Carbon steel,Stainless steel Tolerance gradeGB/T307.1 ... .Appearance inspection8.Rust prevention9.Product packaging 2012 high quality Taper Roller Bearings 30214