In the Kan Ning Tsing(Kansu, Ninghsia, and Tsinghai) Postal District, the exchange rate of silver dollars to Gold Yuan notes was higher than those in other places. The Kan-Ning-Tsing Head Office was authorized to overprint locally, on the domestic letter unit postage stamps, the characters〝限甘寧青區貼用〞(restricted for use in Kan-Ning-Tsing District) in two horizontal lines. The overprint was done in rubber chops in purple.