This Hays Hot Street Clutch kit fits 1955-1985 small and big block internally balanced engines. It offers ultimate Street/Strip performance through matched components. An 11-inch metallic disc with 6 spring helix sprung hub provides superior grip needed for the strip, while the matched diaphragm style pressure plate provides a pedal feel comfortable enough for the street. This provides 30% more clamping pressure and transmits that through a Billet steel flywheel. These matched components provide the peace of mind purchase you've come to expect over the years from Hays.