The S&S Variable Pressure Clutch Plate is the most cost effective kit for upgrading your H-D® stock clutch without any modifications. Up to 40% more pressure for stronger clutch engagement.It works like a lock up clutch with increased torque capacity: strength of engagement increases with RPM. Simple 10 minute installation. Fits behind a stock derby cover and primary cover - No modification required, and can be used with cable or hydraulic clutch controls.