Iridium Power. Denso Iridium Power spark plugs feature a 0.4mm iridium tipped laser welded fine wire center electrode that reduces required voltage and improves firing performance. Tapered cut U-Groove ground electrode increases ignitability and decreases quenching. Machine rolled threads prevent seizing or cross threading during fitting and removal. 100% pre-fired to assure the highest quality possible. Purified alumina powder insulator provides standout strength and thermal conductivity. Five rib insulator prevents flashover. Copper-glass seal bonds center electrode and insulator for a gas-tight seal. IRIDIUM POWER has a low required voltage and a high ignitability, resulting in less misfiring and no spark, the outcomebeing a dramatic improvement in combustion. Engine output is thus increased. The findings of a bench test using a motocycle engine to show the improved combustion from IRIDIUM POWER is shown on the below. Compared to normal plugs, a 0.5ps (1.4%) improvement is seen in output at 110 km/h. *By request/order.