Marine environments place rigorous demands on every component of the ignition system, especially the distributor. The combination of water spray, salt exposure, full throttle acceleration and harsh vibrations all take their toll. The MSD Pro-Billet Distributor is the strongest and most accurate distributor you can put in your boat. The housing is CNC-machined from a billet of 6061-T6 aluminum creating a housing with no porosity. Internally, a QPQ coated shaft is guided by a sealed ball bearing and an extra long sintered bushing for highspeed stability. Each distributor uses MSDs race-proven magnetic pickup to trigger the ignition control. Mounted just above the pickup is a mechanical advance assembly that is easy to adjust so you can dial-in an ignition curve to match your boats application (except PN 8366). For marine use, the distributor cap is bolted to the aluminum base. There are two flame arrestor holes with brass screens machined into the base of the distributor to prevent ignition of gas fumes that may build up in the engine compartment. A special Weathertight Connector is supplied to provide a positive-lock and water resistant connection. The Marine Pro-Billet Distributors have been tested by Underwriters Laboratory and are certified to meet or exceed safety standards for marine ignition systems as set by the U.S. Coast Guard.