Small flat money is the most common form of copper coins, that is, a penny, also known as flat money. It is the smallest monetary unit in the era of using copper coins, with a diameter of about 2.4-2.5 cm and a weight of about 3-4 grams.
Extended data
Qianlong Bao Tong was the currency in circulation during Qianlong period. During the 60 years of Qianlong's rule, Emperor Qianlong put his general plan of governing the country into practice and created the last moderns in feudal society.
This coin was minted during the reign of Emperor Gaozong in the Qing Dynasty (1736- 1795). The Manchu script on the back is more complicated, with detailed price and coin rubbings on it. Gan Long Bao Tong coins are about 25mm in diameter and weigh about 3g.
reference data
Gan Long Bao Tong _ Baidu Encyclopedia