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.“

„ku se; 苦涩 - Bitter and astringent. The nature of new raw Puer is a little astringent and bitter, followed by a sweet aftertaste. However, a bitterness with no sweet aftertaste is not typical of Puer and an astringency which is not comfortable would not be considered good tea. “