ACDelco D323R Professional Ignition Distributor Cap Have metal inserts designed to provide the best possible fit to ensure maximum conductivity between the distributor towers and spark plug wires Easy-to-read locator keys on caps make proper installation simple Equipped with a full anti-arc barrier to reduce the possibility of secondary voltage arcs that can cause an engine to misfire Undergo stringent testing, often under extreme or unusual conditions, to deliver the quality parts you expect from ACDelco Manufactured to meet expectations for fit, form, and function to provide the performance and dependability you expect from ACDelco