MSD iridium spark plugs will fire up your engine for optimum performance. These plugs have been engineered from the inside out for efficient combustion to create the most power possible for your setup. MSD's proprietary design features center tips made from iridium--a super hard material that promotes the best spark as well as increased resilience. They also feature copper center cores, special ceramic material to enhance the dielectric strength of the plug housing, and machine-ground straps enhanced with Yttrium to handle the heat of your high horsepower ignition. On the street, at the track, or up and over the trails, MSD iridium spark plugs will outperform and outlive the competition.