AC Delco R44XLS Iridium Spark PlugThis AC Delco spark plug iridium construction provides outstanding strength, high temperature resistance and Copper core provides great heat transfer and helps maximize plug durability. Iridium offers reliable cold starting, quick acceleration, and smooth engine performance.Benefits of AC Delco Spark Plugs Iridium Construction; High Melting Point; Laswer-Welded; Reliable Cold Starting; AC Delco R44XLS Interchange NGK GR4; NGK BPR5ES; Using the latest in spark plug technology AC Delco is a trusted brand that will provide quick start ups when it matters most.