This disc is sprung centered for noise reduction on solid ACT flywheel. Must use ACT flywheel with sprung hub discs (Flywheel not included). Modified Rigid Street Disc Smooth engagement, quick shifts, increased gear rattle; Premium organic friction materials for heat tolerance, faster recovery from overheating and less wear of mating surfaces, rigid design may increase spline wear; Chromoly hub is heat-treated for strength and durability; Recommended for street and occasional race use; Steel-backed linings for higher burst strength, reduced marcel for quicker shifts 2000802 is a modified rigid-hub street disc featuring premium organic friction materials with high copper content for better heat transfer and steel-backed lining for greater burst strength and durability. These discs are modified with reduced marcel for faster shift action to complement ACT pressure plates. The chrome-moly hub is heat-treated for strength and durability. Rivet design and materials are carefully selected for maximum strength. Lightweight, rigid-hub design allows for quicker shifting and engagement. ACT's street rigid-hub discs provide race-proven performance with street manageability.