I never had a hard time understanding the term copper CORE or understanding that the TIP of the spark is what wears,not the core. Copper is a great conductor of electricity. Thats why so much wiring is stolen. But its a soft metal and would not last as long as nickel alloy in the TIP of a spark plug. I always have tried to define the meaning of phrases. Copper "CORE". Then the ads show the different tips such as a fine wire Iridium. A parts guy at the Chrysler dealer I know I had priced factory Platiumn NGks. Asked me later i]f I bought plugs yet. I told him yes. Autolite Iridiums. He said "won't run right" I sad that is not what Autolite said when I called them and in fact a hair bit smoother idle and might be my imagination but fuel mileage is at a all time high in my truck. Anyhow I have read the same comments from others about idle/mileage when using the Iridium. After reading the aviation piece on Iridium fine wire I see how that did happen. Article says less piston,valve carbon buildup with fine wire Iridium also. The reason my nickname is 'hounddog' was back when I was young I always looked,dug for the CORRECT answer no matter what it might be. Tracking someone down,same thing. A Boss started calling me 'Hounddog' It stuck. I have always called,searched for the REAL answer too a thing or issue. I got a phone number to Bosch R&D once cause I wanted a fuel filter spec and Bosch said 'proprietorship" Got that phone number,called. Got a R&D engineer in the FIELD. Transfered to his cell phone. He answered my question. He could have cared less about proprietorship. He spit the micron rating right out. I thanked in. The 'correct' answer is out there if you dig for it. You also gotta smell the [censored] when it it shot out of someones mounth and look some more.