Genuine 6 pack DENSO Platinum TT 4504 Spark Plug DENSOs revolutionary TwinTip design is a combination of highly durable precious metalsPlatinum and Titanium. The center electrode is created using an extremely durable platinum alloy that allows for the reduction of the tip size to 1.1mm in diameter, while maintaining the life of the plug. The Titaniumenhanced alloy on the ground electrode also increases durability, which is critical to minimize tip erosion and achieve the new TwinTip design Superior ignitability of the DENSO Platinum TT means more efficient combustion, which yields better engine performance in terms of power and fuel economy.