The Dyna S 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.The venerable Dyna S ignition is a time proven solution to the basic ignition and trigger needs of the modern race bike. As a stand alone ignition or as a trigger for the Dyna 4000 Pro ignition, the Dyna S is the standard of performance and reliability.FEATURES Totally self-contained for easy installation All components fit under the point cover, replacing the original points Dyna S utilizes all the time-proven Dyna III circuitry but comes in a smaller, condensed package Use with coils having 3-ohm primary resistance