1、OE Number: Th referencing OE number of this single fire electronic ignition module is 53‑644, which is molded and designed depend on the original data. 2、Fitment: The single fire programmable ignition module is a replacement for S&S, for Ultima, for Revtech, for Shovelhead, for Evolution based motors, replacement for Carbed Big Twin 1970‑1999. 3、Heat Resistance: The single fire electronic ignition module is designed with the latest heat resistant components to prevent failures related to overheating. 4、Convenient Mode Switch: Compared to other models with side mode switches, the cam cover and plug in models have mode switches conveniently. 5、Adjustable Timing Retard: Features an adjustable timing retard suitable for nitrous and turbo applications, offering customization and optimal performance based on your needs. 6、Rev Protection: The ignition module presents engine over rev protection that is adjustable from 6000 to 7500 rpm, improving engine performance and increasing longevity.