This 6 x 3 Kingpinless Ductile Steel Swivel Caster is an ideal choice for those who need a durable product capable of carrying incredibly heavy weight loads, with little concern for floor preservation. Ductile steel caster wheels are made from a combination of special alloys that give it higher weight capacities than cast iron caster wheels. Additionally, ductile steel caster wheels are more economically friendly than drop-forged wheels. They also feature an extra thick walled, heavy duty core, hub, and tread faces . These wheels will never flat spot which makes them ideal for heavy, stationary loads .
For more info, check out Caster Wheel Types.