The Dyna S High Performance Ignition System, designed for Harleys, is a complete self-contained electronic ignition system built with the latest state-of-the-art engineering. This is the same ignition used by top racers over the past 2 decades. The Dyna S is completely housed behind the ignition cover and uses a magnetic rotor with the original spark advancer, so the factory advance curve is maintained. Not legal for use in California on pollution controlled vehicles - Check local laws before installing.