I believe they were 24"X36" in size. I am making a set for the 2009 re-enactment season complete with all the flags from the regimental colors to the flank markers. I have posted a couple of different versions of flank markers so as to show you that they varied quite a bit from unit to unit. In the case of making flank marker flags for a confederate unit you could use a 24" square battle flag as the flank marker.