The carving of the hook-beaked bird on the first closing device is similar to that found on a circular example excavated from the Western Zhou Tomb No. 9 at Zhuyuan'gou, Baoji, Shaanxi province, illustrated in The Complete Collection of Unearthed Jades in China - 14 - Shaanxi, Beijing, 2005, p. 54.
Similar jade closing devices and pendants carved as birds in flight have been unearthed at Qianzhangda, Tengzhou, Shandong province, and include two examples illustrated in The Complete Collection of Unearthed Jades in China - 4 - Shandong, Beijing, 2005, p. 113 (excavated from Tomb No. 3) and p. 114 (excavated from Tomb No. 110).