Demo at K of C in Brooklyn, NY 1969-70. I was 5 feet 11 inches at the time, so I know the height was over 6 feet for the board break, it took me three attempts to make it.
2nd Premium Seminar about traditional kicking (Cha Gi) instructed by Dong Gyu Lee Sa Bom Nim during the Moo Duk Kwan 75th Virtual Anniversary Celebration in 2020.