ACT 600220 XACT Prolite Flywheel Improved engine response and acceleration with lightweight design ACT heat treats the entire forging for strength, toughness and induction hardens ring gears for longest gear life One piece construction allows less opportunity for failure and provides uniform efficient heat transfer from the clutch disc; no more warped inserts or loose ring gears Recommended for high horsepower street or race use All flywheels are CNC machined and dynamically computer balanced for super smooth high RPM reliability