In a horizontal line across the upper part of the stamps is the overprint printed by the Printing Bureau of the Ministry of Finance, Peking reading 〝限吉黑貼用〞(restricted for use in Kirin-Heilungkiang) in Regular-Writing characters. The reason for the overprint is the absence of uniform currency in the North-eastern provinces, each of which issued its own bank notes according to its requirements. Normally, there were no limits on the area of use. In fact, the notes issued by them had their respective circulation zones following local habits and conveniences. In the autumn of 1926 the notes of the Bank of China and the Bank of Communications at Harbin suddenly were depreciated to only 80 per cent of the silver dollars. This difference in the exchange rate caused a serious loss to the Postal Service. In order to prevent the sending of postage stamps from these provinces to other Postal Districts for sale at a profit, a restriction was made at postal counter limiting each purchase of stamps to an amount not exceeding 100 cents (1 dollar), but it was impossible to enforce such a limitation to institutions, public organs, etc., which were in need of large quantity of stamps. Consequently the Sinkiang and Yunnan precedents were followed by overprinting the stamps〝限吉黑貼用〞(restricted for use in Kirin-Heilungkiang).