Wu Zhu, inner rim only on the right side of the hole, head of Jin tilting right, stout outer rim / Inner and outer rims. 23mm, 3.93 grams. Hartill 10.24; Gratzer/Fishman “One Thousand Years of Wu Zhu Coinage” #8.65. SKU Q151-41516
The first "Datong" issue was larger and thicker, weighing around 3 to 4 grams. They were first cast in the Datong Era 1st year (which started in 540 AD), thus the name. These large 1st issue coins are rare.
The Western Wei followed the disintegration of the Northern Wei, and ruled northern China from 535 to 557. As with the Northern Wei state that preceded it, the ruling family of Western Wei were members of the Tuoba clan of the Xianbei.