Platinum is one of the rarest metals on earth and one of the most valuable. However, it also happens to be an excellent material for spark plugs, thanks to its superior resistance to corrosion and erosion in harsh environments - like those inside modern, high-tech engines. DENSO Double Platinum spark plugs incorporate the precious metal on both the center and ground electrodes, not just on the center electrode as with conventional platinum plugs. The result is a significant improvement in spark plug life. DENSO engineering studies show that Double Platinum plugs can run longer with reduced erosion, minimizing spark gap growth throughout the life of the plug.