... certified 3.Low noise,Stable in chemical Taper Roller Bearings XRM Series Material: chrome steel STEEL NO.COMPONENTCSiMnCrMoPS CuNiGCr150.95~1 ... -54-12, Upper H26.02-45-12); Knuckle Upper Lower XRM(Lower H27-48.5-15, Upper H26-48.5-13 ... .853 30209 45 85 20.75 0.474 32212 60 110 29.75 1.170 30210 50 90 21.75 0 ...