The SB10-HDG6 kit from ACT for the Subaru STI features ACT's most popular Heavy Duty pressure plate. ACT Heavy Duty pressure plates use exclusive diaphragm design to increase clamp load, reduce deflection and maximize clutch life. All diaphragms endure a four-stage, heat-treating process for unparalleled performance. ACT pressure plates have precision cover stampings to provide rigidity and consistency. ACT's 6-pad spring-centered race disc features a spring-center construction to properly damp torsional vibrations and resist failure under harsh conditions. ACT spring retainers utilize wraparound spring windows and thicker retainer stampings to provide spring support, reduce stress concentrations, and increase strength and reliability. With the 6-pad spring-centered race disc engagement is harsher, but shifting is faster. The 6-pad spring-centered disc is recommended for larger clutch sizes to absorb more heat. Monoloc is a one-piece, direct replacement or upgrade to the standard, two-piece wedge collar and wire ring featured in pull-type clutches. The spring tension of the segmented retaining ring is carefully calculated and tested for optimal performance. It provides uniform loading on the bearing and pressure plate to assure proper alignment, regardless of driver influence or vehicle modifications. Monoloc's hardened Chrome-moly steel construction will provide years of service.