Note: Fits Type-S Models Only Clutch Masters 2-piece aluminum flywheels are made from the highest quality 6061 T6 or better grade aluminum. This material is chosen for its properties that are much more suitable for the environment than the one piece chromoly units, with regards to heat dissipation and serviceability. The replaceable friction surface used is incredibly tough high carbon steel. This allows mating with any type of clutch friction material without worry. The starter ring gears are made of high carbon heat-treated steel for lasting durability. Clutchmasters button the unit together with military grade fasteners for what many feel is the premier piece in the industry today. Reduced Mass Increases Acceleration 6061 T6 Aluminum Construction Replaceable High Carbon Steel Friction Surface High Carbon Starter Ring Gears Flywheels Meet SFI Spec 1.1 or 1.2 10-30 HP At The Wheels Installs just like a stock flywheel. Constructed of High Carbon steel for the friction surface, which is replaceable.