Two Chinese characters Wu Zhu (=5 Zhu), shallow outer rim / Blank, no rims. 25mm, 2.19 grams. G/F "One Thousand Years of the Wu Zhu coinage" #4.341; Unfinished Hartill 10.27.

These coins are the late Wu Zhu coins are called "Yan Huan Wu Zhu" ("Thread Ring Wu Zhu") because their center was removed. On this coin, removing the inner ring was nor finished. Such unfinished coins are quite rare.