关金券全称为"海关金单位总换券"。简称"关金"。1930年1月南京国民政府规定海关进口税改用金单位代替海关两，时值0.601866克纯金，等于0.4美元、19.7265便士、0.8025日元。但实际征税时并不接受各国金币，而是由纳税人支付关金券。1942年4月后关金券进入流通，与法币比率是1关金折合法币20元。1948年8月发行金圆券后，关金券停用。
由于当时经济的通货膨胀，而出现的大量金圆券、关金券在民间使用，经济的失败，一袋纸币只能购买一块布。当时大量这种不值钱的纸币，随意时间的流逝，这些钱币历经百年的沉积。深沉的历史背景，稀有的发行数量，加上在战争和文革时时期严酷损坏下，保存完的钱币并不好找。另一方面，民国钞又可以视为中国现代纸币的开拓者，留念意义重大，市场潜力正在逐步发招，增值空间无穷，具有极高的收藏价值，历史文化价值：纸币具有一定的升值潜力，钱币交易市场的数据显示，纸币收藏行情波动性不大，没有大起大落之势。时间越长久，越能显示稀 有纸币的价值。难怪大批古钱币玩家发出感叹：几千年的古董钱币不如没年龄的纸币。在感叹之余，他们也把部分注意力转向了纸币，增加了纸币市场的热度。
 
English：
Guanjinquan is called "Customs Gold Unit Total Voucher". Referred to as "Guan Jin". In January 1930, the Nanjing National Government stipulated that the customs import duties should be replaced by gold units instead of customs. The time value was 0.601866 grams of pure gold, which was equal to 0.40 U.S. dollars, 19.7265 pence, and 0.8025 yen. However, when it is actually taxed, it does not accept gold coins from various countries, but taxpayers pay customs vouchers. After April 1942, Guanjinquan entered the circulation, and the ratio with the legal currency was 1 customs gold coin of 20 yuan. After the issuance of gold round vouchers in August 1948, Guanjinquan was suspended.
Due to the economic inflation at that time, a large number of gold coupons and Guanjinquan were used in the private sector. The economy failed and a bag of banknotes could only purchase a piece of cloth. At that time, a large number of such worthless banknotes, the passage of random time, these coins have been deposited over a hundred years. Deep historical background, rare issuance, and severe damage during the war and the Cultural Revolution, the saved coins are not easy to find. On the other hand, the banknotes of the Republic of China can be regarded as pioneers of modern Chinese banknotes. The memory is of great significance. The market potential is gradually being issued, and the value-added space is endless. It has a very high collection value and historical and cultural value: banknotes have a certain appreciation potential. Data from the numismatic market show that the currency collection market is not volatile and there is no great ups and downs. The longer the time, the more it can show the value of thin banknotes. No wonder a large number of ancient coin players sighed: Thousands of years of antique coins are not as old as banknotes. While lamenting, they also turned some of their