This is the highest graded example, qualifier notwithstanding) on the combined PSA and SGC Pop reports. PSA has graded one 5 and one 6 and SGC one 5.5. Those are the only cards within two grades of this one.
The MK qualifier is due to the number "29" being written lightly in pencil in the upper right underneath "CO's" We will say the 7 seems a bit generous as the card has minor to light corner wear which seems a touch heavy for the grade.