Flywheels are manufactured and developed for specific driving environments and recommended based on how each car reacts to changes in rotating mass. Flywheels are NOT a one-fits-all lightweight flywheel, though they can be used for an array of driving habits and racing/high performance applications. Manufactured from only the highest quality steel and aluminium, they are the only flywheels on the market manufactured to a .001 machine tolerance, guaranteeing a flat seating surface for the clutch and smooth rotational qualities for perfect balance and extended engine life.