Speedway Motors LS Harmonic Balancer is 30% more efficient above 5,000 rpm and frees up horse power over stock dampers. The shell is CNC-machined and is designed to mount to the crank hub so the timing marks never change position. It features an inertia ring and hub and is rebuild-able and tunable by replacing the elastomer strips. As an added feature, with the exposed inertia weight marked at TDC, you can tell that the elastomer strips need replacing when the marks start to move. All-around, this harmonic balancer has been built to handle your high performance LS engine with ease. Fits most LS engines and meets SFI Specification 18.1. Free up horsepower over stock dampers, 30% more efficient abouve 5,000 rpm. CNC-machined and designed to mount to crank hub so timing marks never change position. Features inertial ring and hub, rebuild-able and tunable by replacing elastomer strips. Exposed inertial weight at TDC provide indicator that elastomer strips need replaced when marks start to move.