Are you looking for maximum engine protection and performance for your serpentine belt application? These ATI Super Damper serpentine harmonic balancers contain grooves for serpentine belts machined into the outer damper shell. The dampers come standard with six outer grooves for standard OEM drive systems. Specifically designed for high-rpm engines, they're tuned to eliminate the harmful crankshaft harmonics that cause parasitic horsepower loss. They're tunable in the field, rebuildable, and extremely efficient at all rpm.