dental bearing 1.Material:stainless steel ,ceramic... 2.Retainer:Torlon, phenolic or polyimide 3.Series:681,682,68/2.5, ... requirement2.Material for balls: Stainless Steel or ceramic...3.Retainer: Torlon, phenolic or polyimid4.Styles:OPEN,Z,ZZ,RS,2RS5.Precision ...