The Strongway 6in. Swivel Heavy-Duty Dual-Wheel Caster improves stability and swivels more easily than a single wheel with the same size footprint thanks to differential action that reduces the "scrubbing" effect of wide treads against the floor. Double ball raceway provides more strength and more swivel ability. Rugged caster has dual rubber wheels with aluminum core. Constructed of heavy-duty steel with ball bearings. Strong kingpin. Zinc electro-galvanized finish provides a bright look and rust prevention.