... at 50mm H4 Heavy duty type double ball bearing swivel caster wheel Heavy Duty Caster /Four Size available (4'',5'',6'',8'')[ ... plating and Black Electrophoresis finishing available .6.Caster wheel can be changed to Pvc,rubber ,nylon ,pp ,tpr ,cast iron,high ... racks, handcart, transport vehicle ,general usage in market or industrial, etc. 8.Assorted colors (optional)High shock absorption/High abrasion ...