Korea, Joseon Dynasty. Sang Pyong Tong Bo; 1 Mun. Government office of Pukhan Mountain Fortress. (3.79g; 25.6mm). O./ 常 平 寶 通 [Sand p'yong tong bo; Department of Korean Yi Dynasty, currency unit]. R./  经 四  [(Kyong): Pukhan Mountain Fortress (si): series 4] . Mandel#31.1.4 $20