The fundamental design of this new generation of Denso Iridium Power spark plugs retains the proven features used in Denso's OE products and combines a revolutionary Iridium alloy with laser welding technology that allows Denso to harness the power of Iridium. Using Iridium, which is six times harder and eight times stronger than platinum, the tip can be shrunk to only 0.4mm. This means the voltage requirements are decreased while firing performance is greatly improved. A U-Groove has been cut inside the ground electrode to maintain the large volume of space required to form the nucleus of a flame. While still keeping the required voltage low, this powerful technology enables excellent firing performance without increasing the spark gap.