"XJ" frets are extra jumbo...a little taller and a little wider than jumbo frets. As most ESP's are made for metal/hard rock, they all have XJ frets. Don't let that turn you off though. Fretboards with jumbo or XJ frets require less force on the board to get the note out. Some also say that their fingers don't drag as much on the fretboard during fast runs when using bigger frets.