... :stainless steel ,ceramic... 2.Retainer:Torlon, phenolic or polyimide 3.Series:681,682,68/2.5,692.. dental bearing:1.Material for ... rings: stainless steel AISI 440c or as requirement2.Material for balls: Stainless Steel or ceramic...3.Retainer ... /2.5,692,69/2.5,L520,683,693....etc dental bearing