This unusual shape appears to be based on early jade prototypes of smaller size, such as the example of late Eastern Zhou date in the Winthrop Collection illustrated by M. Loehr, Ancient Chinese Jades, Fogg Art Museum, Harvard University, 1975, p. 342, no. 507. As with the present example, two bi carved with comma spirals and with angular loops with dragon scroll terminals projecting from the outer edges are joined by a fluted ring or hinge. Unlike the present example the two bi have two additional small dragon or bird scrolls projecting from the outer edge to balance those forming the terminals of the loops.
Other Qing dynasty archaistic hinged twin-bi of this type have been published. One also of yellow jade, dated to mid-Qing, in the collection of the Palace Museum, is illustrated in Zhongguo yuqi quan ji - 6 - Qing, p. 171, no. 250; another in what appears to be greyish-green jade, in the Qing court collection, is illustrated in The Complete Collection of Treasures of the Palace Museum - 42 - Jadeware (III), Hong Kong, 1995, p. 159, no. 128. And a white jade example in the collection of His Majesty the King, Windsor Castle, was included in the International Exhibition of Chinese Art, Royal Academy of Arts, London, 1935-36, no. 2327.