Pertronix D7132710 Flame-Thrower Vacuum Advance Black Male Cap Billet Electronic Distributor with Ignitor III Technology for Ford 351C Plug n Play billet distributors are designed for maximum ignition performance at a price you can afford Our Billet I3 distributors ship with Ignitor III multi-spark rev limiting modules Precision CNC machined 6061-T6 billet aluminum housings are lightweight yet offer maximum strength Each billet distributor is hand polished and buffed to a high luster Tempered distributor shaft has low torsion displacement for accurate timing and extended operational life Adjustable mechanical advance with proprietary limiting function permits multiple settings Distributors are factory set with a performance advance curve and are provided with additional springs for custom advance