DENSO Standard X24EPRU9 spark plug

U-Groove Ground Electrode Promotes Ignitability and Decreases Quenching.- Fully Projected Insulator Reduces Carbon Fouling.- Machine Rolled Threads Prevent Seizing or Cross Threading During Installation and Removal.- 100% Pre-Fired to Assure the Highest Quality Possible.- Purified Alumina Powder Insulator Provides Exceptional Strength and Thermal Conductivity.- Five Rib Insulator Prevents Flashover.- Copper-Glass Seal Bonds Center Electrode and Insulator for a Gas-Tight Seal.