These Pro/Street SBC harmonic dampers by Pro Race Performance Products have been machined to tolerances far exceeding those used by OEM’s. Dampers are lightweight, weighing 4.6 pounds. These dampers feature an amazing overall surface finish. Permanent rolled-in timing marks are very visible and will never fade or become less visible! Internally balanced. Sold each. Pro/Street 21262 Harmonic Damper. 6.10" outside diameter. 4.6 pounds. Internally balanced. For 283-350 Small Block Fits Chevy. Features “Nodular Iron Construction – Most cast dampers are manufactured from gray iron castings. Nodular iron is over 30% stronger than gray iron. Bonded Elastomer – Outer ring and inner hub are bonded (vulcanized) to the elastomer. This minimizes the potential for the outer ring to move on the hub, losing true TDC position. Precision Balanced – Dampers are machined and precision balanced. 60o of permanent easy to read timing marks (40o on SBFits Ford models)