AC Delco 41-101 Iridium Spark PlugThis AC Delco spark plug iridium construction provides outstanding strength and high temperature resistance. Iridium allows for smaller, more efficient electrode designs for improved cold starting and quicker acceleration with smooth engine performance. Iridium Construction; High Melting Point; Laswer-Welded; Reliable Cold Starting; AC Delco 41-101 Interchange Volvo 21467472; Donovan 203052; NGK ITR4A15; Using the latest in spark plug technology AC Delco is a trusted brand that will provide quick start ups when it matters most.