This pair of exceptionally large censers would have decorated the the imperial palace, and been used as charcoal-burning braziers to warm the halls and throne rooms which became very cold in winter. Many censers and braziers of different designs and sizes are known, but this pair appears to be unique.
Compare with other large and similarly impressive sets of cloisonne enamel vessels: a pair of imperial braziers with elephant-head legs, from the C. Ruxton and Audrey B. Love Collection, sold in our New York Rooms, 20 October 2004, lot 354; a smaller example which still stands by the nuptial bed in the Palace of Earthly Tranquility in the Beijing Palace, illustrated in La Cite Interdite: Vie publique et privee des empereurs de Chine (1644-1911), 1996, p. 12, fig. 10; an octagonal pair which can be seen standing on either side if the emperor's steps up to the throne in the Palace of Heavenly Purity in the Forbidden City in Splendors of China's Forbidden City - The Glorious Reign of the Emperor Qianlong, Field Museum, Chicago, 2004, pl. 32.