... needle roller bearing: HK, BK, HK RS, HK 2RS, BK RS, F, FH, MF, MFH, FY, MFY, HF, HFLWe are professional manufactuer .1. Model: LZ series, HK SERIES, BK SERIES, HK-RS SERIES, BK-RS SERIES ... , FFH SERIES, MFH SERIES, FY SERIES, MFY SERIES, HF SERIES, HFL SERIES etc 2. Materials: GCr15, GCr15SiMn, ...