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.“

„Depending on the desired product and speed, from quickest and tightest to slowest and loosest, pressing can be done by a hydraulic press, which forces the tea into a metal form that is occasionally decorated with a motif in sunken-relief. Due to its efficiency, this method is used to make almost all forms of pressed pu'er.“