Extra Heavy-Duty Casters is built from heavy plate steel with hardened bearings and sealed raceways for extra heavy load capacities. It is equipped with a hardened 1″ king bolt welded to the top plate. It provides superior performance, wide selection, and reliable service. Its extra thick hot forgings, guaranteed-for-life integrally forged kingpin and precision tapered thrust bearing combine to defy comparison. It is also available in a dual-wheeled version. It has a corrosion resistant zinc plated finish. The patented kingpin less single ball precision raceway assists the caster to turn and control easily. It features precision tapered thrust bearing with dust seal in lower raceway. It has replaceable bolt axles and hardened steel bushings. Bearing seal keeps dirt out, while greasing purges old lube.