1969-81 GM 305/350/396/400/455 Clutch Kit 11 in. diameter, 26-spline;Great drivability for power levels up to 450 horsepower; Smooth, chatter-free operation using top quality organic composite friction surface material; Upgraded damper springs gives up to 30% more clamping pressure than stock OE clutch; Clutch disc features heavy-duty hub spring assembly for increased load capacity; All Street 450 clutch kits come complete with pressure plate, disc, release bearing, and alignment tool unless otherwise noted;