DENSOs Iridium Long Life plug is fast becoming the standard for todays high-tech engines. The properties of DENSOs patented Iridium alloy have broken through the spark plug technology barrier. Employing a revolutionary new 360 laser welding process, DENSO has created a spark plug unlike anything on the market today. Designed for durability under the most extreme conditions, DENSOs patented Iridium alloy is six times harder and eight times stronger than conventional platinum and can handle temperatures in excess of 4,000F.