Vibration Damper. Fits all E-Type six cylinder Jaguar engines. A must for high RPM use or the enthusiast looking for a smoother-running engine. Manufactured for the Jaguar engine, not adapted from another engine as some others. Each unit comes accurately marked 0-40 degrees for precise timing. Damper is supplied pre-drilled to accept standard Jaguar crank pulley. Ideal for racing and street engines where smoothness and reliability are important.