Unlike undampened underdrive pulleys, which offer no protection to high-performance engines, the ATI Super Damper provides balanced dampening of torsional crankshaft vibrations at all RPM levels. The ATI Super Damper comes with laser-etched timing marks and is a direct replacement for the OEM unit. The ATI Super Damper is a critical component for all high-performance cars to help protect against engine harmonics and features four-groove and five-groove serpentine belt drives on the outer shell to utilize the factory serpentine belt set-up. All ATI Super Dampers exceed SFI 18.1 Safety Certification and are approved for competition use.