ACT's 4-pad rigid race discs are made with high quality, ceramic friction materials that produce 28 percent more friction and torque capacity over organic materials. The chrome-moly hub is heat-treated for strength and durability and the lightweight, rigid design allows for quicker shifts and smooth, trouble-free service. With the 4-pad rigid race disc, engagement is harsher but shifting is faster. The 4-pad rigid race disc features top grade rivets to securely fasten the part together. The rivet design and rivet materials are carefully selected for maximum strength. The 4-pad rigid race disc is well-suited for the smaller disc sizes in smaller engines. All friction pads are measured, sorted and matched before assembly to ensure that each disc is uniform in thickness. In addition, all ACT race discs are certified as meeting SFI Specification 1.1 and are legal in all racing organizations that require SFI certification.