The S&S Variable Pressure Plate Clutch is a sophisticated lock-up clutch and the most cost-effective way to upgrade the stock H-D® clutch; without modifications to the clutch itself. The basics are simple: Engine power increases with RPM and the faster the S&S Variable Pressure Plate Clutch rotates; the stronger the clamping force. This helps prevent clutch-slip and saves your clutch plates. - Simple bolt-on installation - No modifications required - Cost effective - Dependable - Up to 50% more clamping force - With the OEM clutch spring 140ft-lbs can be handled - 15 minute bolt-on installation - Installation can be done through the derby cover - Primary cover does not need removal