... ball bearings have been manufactured from aluminum, 300 series stainless steel, 17-4PH and other metals. Some ... special ball materials include CRES 440C, 300 series stainless steel, silicon nitride, and M50 steel.Freerun ... to 12inches .6.ET,ER Series Thin Section Bearings7. Extra Thin Metric Series from 10.00—90.00 ... mm8.Extra thin Metric Flanged Series from 10.00—50.00mmIf you do not ...