... Hardness: 62~67HRC steel ball material:GCr15 Best in quality linear ball cages in different types and specifications for your choice, also ... 004lowµ:0.005~0.008Shrink fit : 0.012~0.0005mmMaterial: plastic (resin ),aluminum alloy(bushing),copper(bushing),steel(ball).Hardness: ... can made of other material ,just like ceramic,plastic etc.)NO 1: Plastic bushing (blue,white colour,POMS,POMBS,POMM,POMBM ...