6" x 2" Energy Ductile Steel Kingpinless Swivel Caster Heavy Duty 2000# Cap6" x 2" Energy Ductile Steel Wheel Kingpinless Swivel Caster The Ductile Steel wheel provides extreme weight capacity for its size. The ductile steel is graphite rich, which is stronger and more durable than even our standard semi steel wheels. With a tensile strength of 45,000 PSI, you'll be hard pressed to find a job that needs a stronger wheel. Tread: Slightly Crowned Solid Cast Ductile Steel Core: Solid Cast Ductile Steel Bearing: Roller Bearing