... Industrial Caster(3.0mm) Ball Bearing:3", 4", 5" BB: Polyester PU Reinforced Industrial Caster (Roller Bearing): 3", 4", 5" Mediu-Loading Heavy Duty ... Caster Series AA:Heavy-duty Rubber Cast-Iron Industrial Caster(Roller Bearing)(6.0mm),4"--8" BB: Heavy-duty Polyester Plastic ... Caster Series AA:Eagle-Bracket Rubber Cast-Iron Industrial Caster(Roller Bearing) (6.0mm), 6",8" BB: Eagle-Bracket Polyester ...