All billet flywheels are not created equal! RAM billet steel and aluminum flywheels are fully machined and assembled in house. That means when RAM billet flywheel, it is already surface ground, already balanced, and ready to install out of the box. A key feature of RAM aluminum flywheels is the steel insert. A flywheel insert must have enough mass to wick heat away from the clutch without distorting. RAM uses a 0.250 Inch thick inset that is riveted in before the flywheel is surface ground. This assures a parallel friction surface with no run out and enough material to adequately wick the heat while maintaining flatness over time that thinner inserts simply cannot do. All RAM billet flywheels are SFI certified.