Extra heavy duty type: painted coating & tapered bearing. The steel bracket bears high load and promising smooth operation. However combining with rubber wheel, this strong bracket is just showing 50 - 75% of its ability.
Very thick, that is true for both steel bracket and PA wheel. The caster itself is heavy and have strength to support up to few tons per caster. The Swivel head is combined of Flat and Cone Bearing so you will have no trouble operating.