ACDelco 41-821 Professional Platinum Spark Plug (Pack of 1) One-piece, fired-in suppressor seal blends three glass types for a gas-tight seal. Reduces radio frequency and engine interference, regulates spark plug energy and seals against compression pressures for long life Double platinum point pad on center and ground electrode offer increased durability and consistent voltage demands to reduce wear on ignition system 100% Pure Copper Core results in cooler electrode temperature for enhanced durability and superior fouling resistance