The center electrode is fine wire platinum for better starts, superior acceleration and better fuel econom. This plug is basically an efficient plug.
Iridium plugs , the latest evolution of spark plug technology. The iridium center electrode is both stronger and harder than platinum. This allows NGK engineers to design an ultra-fine (0.6mm)center electrode reducing the voltage requirement for spark. This allows for a brighter, stronger spark from your existing ignition system. The ground electrode has a tapered cut at the firing end which reduces quenching for better flame core growth and increased ignitability. The combination of fine wire center electrode and tapered cut ground will increase performance, improve acceleration, and fuel efficiency
found it in a search so iridium is best