Denso, a leader in high performance spark plug technology, has introduced a patented new design that uses an exotic Iridium metal alloy to replace the traditional platinum center electrode. Because of Iridium's hardness, superior strength and melting point that is 700 degrees C higher than platinum, Denso was able to reduce the center electrode diameter to just .4mm compared to a typical platinum 1.1mm electrode. The result is a spark plug that takes up to 5,000 volts less to fire and will resist electrode erosion for up to 100,000 miles. You won't find a better spark plug for severe duty and for faster cold starts, regardless of temperature.