... ,51100,51200,51300, Inch and metric series etc.MaterialChrome Steel ,GCr15,Carbon steel,Stainless steelNoise standardZ1, Z2, Z3, Z4Quality standardISO 9001 ... Rust prevention9.Product packaging Company Profileqinngdao rich Bearing Manufacturing Co., Ltd. is a specialized enterprise for the production of tapered ... 2012 hot sales ! super quality and high precision bearings ltd international certification