FX Racing Lightweight Chromoly Flywheels are made from 4140 one-piece forged chromoly steel. They are specifically designed to reduce weight and inertia for better engine response. Most incorporate special design features to enhance the air flow to improve the cooling of the clutch. The ring gear teeth are milled onto the flywheel unlike an aluminum flywheel where the ring gear is pressed onto the flywheel which has the possibility of separating from the flywheel. All FX Racing Chromoly flywheels have passed engineering tests to 12,000 rpm. After professionally installed the flywheel requires a 500 mile break-in period. Ultra heavy-duty and weighs only Meets or exceeds SFI 1.1 certification Made from 4140 forged chromoly steel (2X stronger than billet steel) FX Racing Lightweight Chromoly flywheels incorporate special design features to enhance the airflow for improved clutch cooling FX Racing Lightweight Chromoly flywheels work with every clutch including Exedy, ACT, Fidanza, Clutchmasters CAD designed, CNC machined and computer balanced Ring gear count: 124