ACDelco D329A GM Original Equipment 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 GM-recommended replacement part for your GM vehicles original factory component Offering the quality, reliability, and durability of GM OE