For our 2017 Explorer w/2.3 EcoBoost the factory plugs are Motorcraft SP-537, Iridium plugs. The replacement plugs are Motorcraft SP-550, Platinum plugs. I replaced the plugs last year and used the SP-537 plugs. I don't see those plugs any more, only the SP-550. If you want Iridium I guess you need to buy the NGK plugs that are the equivalent of the SP-537, NGK lists them as OEM plugs on their site, I don't remember the part #, sorry. You would think with a GDI turbo engine Ford would stick with the factory Iridium plugs.