Bosch Platinum +4 Spark Plugs are designed with a revolutionary firing spark. Surrounding the center electrode, which contains 75% more platinum than previous Bosch platinum plugs, are four "surface air gap" ground electrodes made from special wear resistant nickel yttrium alloy results in a longer, more powerful spark that reduces misfires, increases fuel economy up to 4.8 percent over other competitive spark plugs, lowers emissions and speeds up acceleration.