According to U.S. Army Patches, Flashes and Ovals, this organizational flash was approved on 28 October 1981 for wear by personnel assigned to the U.S. Army Special Forces (School) Training Group—but also notes that it had been worn for nearly twenty years prior to that official authorization and would continue to be worn up until 1989. Between 1972 and 1989, the unit the flash represented was redesignated no fewer than give times: for the Military Assistance Student Battalion (1972), Special Forces School Battalion (1981), Special Forces Training Battalion (1983), 1st Special Warfare Training Battalion (1985), and the 1st Special Warfare Training Group (1989).
It should be noted that while The Institute of Heraldry does not have a description or history of this organizational flash, it does state that it was designated for the U.S. Army Special Operations School, as opposed to the U.S. Army Patches’ claim it was for the Special Forces School.