... 3", 4", 5" BB: Polyester PU Reinforced Industrial Caster (Roller Bearing): 3", 4", 5" Mediu-Loading Heavy ... 8" BB: Heavy-duty Polyester Plastic-cored Industrial Caster(Roller Bearing) (6.0mm),4"--8" CC: ... 8" BB: Eagle-Bracket Polyester Cast-Iron Industrial Caster(Roller Bearing) (6.0mm),6",8" CC: ... Blue-Bracket Polyester Cast-Iron double brake Industrial Caster(Ball/Roller Bearing) sizes: 4"-12" Square ...