SPEC flywheels are CNC manufactured at an unheard of .001 tolerance, in an industry where the standard is .010. This precision manufacturing process ensures perfect balance and a perfectly flat bedding surface for the clutch disc, both of which also contribute to the ultimate in safety for competitive environments. All SPEC flywheels carry SFI certification. SPEC billet steel and billet aluminum flywheels are recommended as replacements for OEM cast steel flywheels in street high performance and racing applications. Both the steel and aluminum SPEC units are rebuildable and feature a replaceable steel friction plate that is made from a friction-enhancing steel metal specially formulated for optimum clutch bedding and holding power. The aluminum and steel materials provide a light and medium weight option for all types of racing. Your engine, gearing and vehicle weight are factors in determining which flywheel would be best suited for your application.