I had a very hard time finding BR9EYA plugs to carry as spares (most auto parts stores don't carry them yet). * Talked to my dealer, and he said the only difference between them is the split in the electrode the EYA has. *He also felt that the EYA burned just slightly hotter than the ES. *Also, EVA plugs can be used (as long as they're BR9). *I think that is a plated plug, not sure with what though. *Bottom line, as long as it's a BR9, you can use it, regardless of the letters after.