... 4mm Fork thickness is 3mm Rolling castor wheel, light duty casters, Medium duty casters, medium heavy duty caster, Heavy duty casters, PU caster,PP Caster,PVC Caster ... . Eletroconductive caster,elastic rubber wheel.Anti static caster. Transparent Casters, Skate castors, wheels, furniture caster, Racking caster wheel,Wringer caster wheel,Pallet wheel. trolley caster.