Pertronix (D7500701) Replacement Ignitor III Module for 4-Cylinder Flame-Thrower Billet Distributor Plug n' Play billet distributors are designed for maximum ignition performance at a price to afford 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