This is our smallest (6.1" O.D. x .75" thick) damper for small block Chevys. The high performance street Powerforce model weighs 5.08 pounds, while the Powerforce+Plus race model weighs 5.7 pounds. Both models are made of 1045 steel (all other Powerforce dampers are nodular iron). Keep in mind that the inertia ring weight is what performs the actual damping of the rotating assembly. A light weight damper like this will not achieve the degree of damping that heavier dampers do. But many racers or performance enthusiasts want the lightest damper they can get that will still do the job, and these two dampers fill that requirement. Both models include 60° of timing marks with engraved marks every 90 degrees.