Aluminum Flywheel.When selecting replacement friction kit, confirm bolt pattern for your specific flywheel before purchase.High Performance And Lighter Weight To Free Additional HorsepowerHeat Treated Friction Plate For Optimum Grip And Long Life40-60 Percent Lighter Than Stock For Quicker AccelerationMilitary Spec Fasteners For Reliability And StrengthReplaceable Hardened 1050 Steel Ring GearBillet 6061 T6 Or 2024 T4 Aluminum BodyLower MOI For Faster Throttle ResponseStepped Dowels On Most ApplicationsBolt-on Replaceable Friction Plate