Denso (4507) PQ16TT Platinum TT Spark Plug, (Pack of 1) Twin-tip technology with 11 mm platinum center electrode and 11 mm titanium enhanced ground electrode Improve fuel economy, better acceleration and faster starts than all other single platinum plugs Purified alumina powder insulator provides exceptional dielectric strength and thermal conductivity, allowing the material to stand up to extreme stress Purified alumina powder insulator provides exceptional dielectric strength and thermal conductivity, allowing the material to stand up to extreme stress