8" x 2" Energy Saver Ductile Steel Swivel Caster Medium Duty, 1500 lbs. Cap8" x 2" Energy Saver Ductile Steel Wheel 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: Solid Cast Ductile Steel Core: Solid Cast Ductile Steel Bearing: Roller Bearing Rig: Zinc Plated Swivel