Fidanza flywheels are manufactured from the highest quality 6061-T6 billet aluminum. They feature excellent heat dissipation and weight reduction. The replaceable friction surface is constructed from 1045 steel and attached with military-grade aerospace fasteners. Fidanza billet aluminum flywheels also feature a 1050 heat-treated steel ring gear that's pressed on and secured with Grade 8 button screws. They also use a stepped dowel system, so that when they're installed they are locked into place. No chromoly can compete with the awesome serviceability, strength, and superior design of the Fidanza billet aluminum flywheels.