Pressed steel swivel caster, heavy duty casters, with steel spring. Heavy duty wheel with Blickle Softhane®. polyurethane tread, with aluminum wheel center. Bracket: Made of heavy pressed steel, with heavy fork and top plate, very strong bolted and secured central kingpin, double ball bearing in the swivel head, additionally reinforced by the integration of four specially shaped and hardened bearing seats resulting in a very high resistance to shock and impact loads. Rugged hinged plate construction with maintenance-free steel spring mechanism. Bolted wheel axle. Zinc-plated, blue-passivated, Cr6-free.