Four Chinese characters - Qian Long Tong Bao in Chinese / Boo Gui in Manchu. The Board of Revenue mint. 24mm, 3.10 grams. Hartill 22.280. 

Emperor Gao Zong (Qian Long) (25 September 1711 - 7 February 1799) was the fifth emperor of the Manchu-led Qing Dynasty, and the fourth Qing emperor to rule over China proper.