Externally Balanced Harmonic Balancer for High Performance 700 SCi Mercury Marine Sterndrive Engines with SFI 18.1 Rating for the highest quality. The Balancer features an all anodized aluminum case design for light weight, stress-proof steel hub and 1040 steel inertia rings for durability. Wet clutch friction design style with precision machined harmonic dampening for street and race engines.