Item No.: GE4~GE12E, GE15ES~GE300ES, GE15ES-2RS~GE300ES-2RSInner Race: Gcr15 Steel,hardened HRC 58-64,surface phosphated. Outer Race: Gcr15 Steel,hardened HRC 54-60,surface phosphated. Sliding contact surfaces: Steel/SteelPhone: +86-592-580 8851 / +86-592-580 7618Email: sales@ldk-bearing.com ; benjamin@ldk-bearings.com