Denso iridium long life spark plugs are factory installed on luxury vehicles by automakers such as GM, Toyota, Honda and Mitsubishi. 0.7mm iridium tipped laser welded fine wire center electrode and platinum tipped ground electrode. Tapered cut ground electrode increases ignitability and decreases quenching. Machine rolled threads prevent seizing or cross threading during installation and removal. 100% pre-fired to assure the highest quality possible. Purified alumina powder insulator provides exceptional strength and thermal conductivity. Five rib insulator prevents flashover. Copper-glass seal bonds center electrode and insulator for a gas-tight seal.