This damper is intended for use on externally balanced 383 or 400 small block Chevy engines. They feature a bolt-in counterweight which can be removed for neutral balance applications. These dampers are actually identical to the 80002 and 90002, except they also include the bolt-in counterweight. Both dampers have 60° of easy to read timing marks and engraved marks every 90 degrees. These are ideal dampers for high performance street or racing applications, and their somewhat heavier weight provides maximum damping characteristics. These dampers, especially the Powerforce damper for high performance street applications, are extremely reasonably priced and yet are very high quality.