The patented ATI Super Damper is the only damper designed exclusively for high performance engines: Eliminates torsional crankshaft vibrations Exceeds SFI 18.1 specs Laser engraved timing marks Black zinc chromate finish ATI has designed a 5.5 damper for the Nissan SR20DET for high horsepower street & race use. This new design is a direct replacement for the stock OEM damper. The heart of this unit is the tried and true damper within a damper design that has put ATI ahead of the rest. Specs: Total Weight: 3.6lbs. 3 Ring Design for A/C, PS, Main Belts. Damper is not underdriven. Needs to be rebalanced every 10 years for street cars over 400hp.