Bosch Double Iridium Spark Plugs feature both an iridium firing pin and an iridium ground electrode inlay that offer higher performance and 4X longer life compared to standard copper spark plugs 360-degree laser welded ultra-fine wire iridium firing pin provides better ignitability - reducing voltage requirements up to 24% - and enhanced durability Nickel-plated rolled threads provide superior resistance to corrosion and do not require anti-seize - making installation quick and easy Bosch Double Iridium spark plugs are pre-gapped at the factory and ready to install right out of the box - gap adjustment prior to installation not required Meets or exceeds manufacturer design requirements for OE fit, form, and function for modern gasoline engines - including Gasoline Direct Injection (GDI) engines Compatible with select vehicles (Note: engine affects fitment - verify fitment details with amazon confirmed fit fit checker above): BUICK: 1987-93 Century, 2009-11 Lucerne, 1988-93 Regal, 1987-89 Skyhawk, 2006-07 Terraza; CADILLAC: 1986-88 Cimarron Compatible with (continued): CHEVROLET: 2002-06 Avalanche 2500, 1987-93 Beretta, 2001-02 C3500HD, 1987-94 Cavalier, 1987-90 Celebrity, 1987-93 Corsica, 2001-02 Express 3500, 2006-11 Impala, 1990-94 Lumina, 2006-10 Malibu, 2006-07 Monte Carlo Compatible with (continued): CHEVROLET: 2001-06 Silverado 2500 HD, 2007 Silverado 2500 HD Classic, 2001-06 Silverado 3500, 2007 Silverado 3500 Classic, 2001-06 Suburban 2500, 2006-09 Uplander; GMC: 2001-02 C3500HD, 2001-02 Savana 3500 Compatible with (continued): GMC: 2001-06 Sierra 2500 HD, 2007 Sierra 2500 HD Classic, 2001-06 Sierra 3500, 2007 Sierra 3500 Classic, 2001-06 Yukon XL 2500; OLDSMOBILE: 1987-93 Cutlass, 1987-89,1993 Cutlass Ciera, 1987-89 Cutlass Cruiser Compatible with (continued): OLDSMOBILE: 1988-93 Cutlass Supreme, 1986-88 Firenza; PONTIAC: 1987-91 6000, 2006-10 G6, 1988-93 Grand Prix, 2006-09 Montana, 1991-94 Sunbird; SATURN: 2007-08 Aura, 2006-07 Relay, 2008-10 Vue