PerTronix D100700 Flame-Thrower Plug and Play Vacuum Advance Black Cap Billet Electronic Distributor with Ignitor II Technology for Chevrolet Small Block/Big Block Precision CNC machined 6061-T6 billet aluminum housings are lightweight yet offer maximum strength Our Billet I2 distributors ship with Ignitor II modules factory installed 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 Upper ball bearing and extra long oil impregnated bronze lower bushing work together to reduce friction and provide shaft and advance mechanism stability reducing high RPM vibration