Pertronix D7172420 Flame-Thrower Plug and Play Top Exit Style Cap Vacuum Advance Electronic Distributor with Ignitor III for British 25D 4-Cylinder Engine All new lightweight cast aluminum housings Tailored advance curve for optimal performance and drivability Ignitor III multi-spark rev limiting modules Integrated digital REV limiter with LED feedback for precise RPM setting Peak current level is reached just prior to spark for maximum energy without the heat build-up, increasing coil and module life