Pu-erh tea

„Nèi fēi (内飞 or 內飛): A small ticket originally stuck on the tea cake but now usually embedded into the cake during pressing. It is usually used as proof, or a possible sign, to the authenticity of the tea. Some higher end pu'er cakes have more than one nèi fēi embedded in the cake. The ticket usually indicates the tea factory and brand.“

„The most classical Puerh Tea is the Bingcha, recorded in Yong-Zheng 13th year in Qing Dynasty (1735). Each tea cake weighs 7 Liang (357 grams). Seven cakes make 1 Tong (wrapped in leaves), weighing 49 Liang. It was sold in nice places and also was exported abroad. It was re-named as "Yunnan Qizi bingcha - Yunnan seven cake tea" during the Cutural revolution.“