ACT pressure plates feature a special, single diaphragm design to dramatically increase clamp load without the adverse effects of double-diaphragm type clutches. Effective diaphragm designs are used to increase clamp load, reduce deflection and maximize clutch life. All diaphragms endure an exclusive four stage, heat treating process for unparalleled performance. The Heavy Duty pressure plate is one of the most popular models offered by ACT. It provides a clamp load increase of about 20-50% and most meet SFI Spec 1.1 to ensure safety.