NGK Ruthenium HX is designed for newer engines which demand high ignitability. Projected Square Platinum Electrode (PSPE) design promotes spark energy concentration and ignites a wider range of air-fuel ratios, offering improved performance in rich or lean engine conditions. 0.4mm Ruthenium alloy fine wire center electrode and 0.8mm platinum fine wire ground electrode. Trivalent metal platinum provides superior anti-corrosion and anti-seizing properties. Corrugated ribs prevent flashover. Pure alumina silicate ceramic insulator provides superior strength and better heat transfer. Copper core aids in heat removal.