This balancer is a brand new SFI series harmonic damper that is 18.1 SFI Certified. It is intended for racing applications and high performance street applications to 10,000 RPM plus. This damper is dimensionally the same as the O.E. 454 damper with an 8" O.D. and a 1.732 inertia ring thickness. The damper features 60° of clear, easy to read timing marks along with engraved marks every 90 degrees. The dampers both feature a bolt-in counterweight which can be removed if a neutral balance damper is desired. The damper comes with the correct counterweight. The SFI-spec damper for all-out racing are extremely affordable dampers.