This mirror appears to be quite rare, especially the inclusion of the animal masks in the band of zodiac animals on the rim. The semi-circles that separate the animals in the main field are a continuation of a decorative motif first seen on Eastern Han dynasty mirrors, which seem to disappear after the Sui dynasty. A mirror of similar type illustrated in Ancient Bronze Mirrors from the Shanghai Museum, Shanghai, 2005, pp. 216-7, no. 70, also has two lean animals encircling the knob, but within an octagonal border, has more animals in the main field between the semi-circles, and the animal masks separating the animals of the zodiac in the outer band are shown in profile rather than full face as they bite the border. A mirror of this latter type in the collection of the Gotoh Museum is illustrated in the exhibition catalogue, Tang Mirrors, Sen-Oku Hakuko Kan, Kyoto, 2006, p. 13, no. 7.