... like ceramic,plastic etc.)NO 1: Plastic bushing (blue,white colour,POMS,POMBS,POMM,POMBM,POMT,POMBT type;NO 2 ... colour,ALBS,ALS,ALBM,ALM,ALBT,ALT type );NO 3:Copper bushing(copper-colored, CUS, ... CUM,CUT type).Also each type with the Standard Kind,the Compact Kind ... Kind has more steel balls than the Standard type with the same specifications, it is more reliable ...