According to Curtis Evarts and Wang Shixiang in Masterpieces From the Museum of Classical Chinese Furniture, Chicago and San Francisco, 1995, p. 30, folding stools in zitan are extremely rare. The authors note that while similar examples exist in huanghuali, their members are often carved with decorative elements. The present stool may have been left unadorned to highlight both the elegant shape and attractive grain.
Perhaps the only other known example in zitan is that illustrated by Grace Wu Bruce in Chan Chair and Qin Bench: The Dr. S.Y. Yip Collection of Classic Chinese Furniture II, Hong Kong, 1998, pp. 78-9, no. 10, where it is dated to the 16th/17th century. A closely related huanghuali folding stool is published by Wang Shixiang in Connoisseurship of Chinese Furniture: Ming and Early Qing Dynasties, vol. II, p. 31, no A40. Wang refers in vol. I, p. 35, to the illustrated example as being imperial, and discusses the construction, with metal rods passing through both legs and being secured by decorative washers called huyanqian, which can also be seen on the present stool. Wang also notes that the construction, material, hardware and weaving are all of superior quality, and indicative of highly skilled and talented carpenters.