Bosch Spark plugs are designed to meet very specific requirements of engine manufacturers. Although all spark plugs look similar, subtle differences in design and materials used can have a significant effect on performance. One of the most influential features of a spark plug is the electrode material. Bosch spark plugs generally use one of the three electrode materials: Nickel-Yttrium, Platinum and Iridium. Platinum and Iridium are known as precious metals and provide greater durability. Bosch has tested every application to ensure that the spark plugs we recommend match the exact specifications of the engine manufacturer.