Frame: Heavy-duty 2″x 4″ oval and 3″ round 11 gauge tubular steel. Powder Coated Finish: The Electrostatic Powder Coat offers a durable, maintenance free finish. Bearing System: Precision Steel Ball Bearing system provides a smooth, maintenance free action. Pulleys: Fiberglass reinforced nylon. Weight Stacks: Two 150lb. commercial weight stacks with solid guide rods and center drilled weight plates.