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.“

„There is also a lack of formal definition for "gu shu." Some say "gu shu" should only refer to trees over 300 years of age, that is left to grow tall, and not pruned back. But in reality, most "gu shu" trees are cultivated, which entails annual pruning to encourage regrowth & lower branches for easy picking. A lot of "gu shu" on the market comes from trees as young as 100 years old, some of which is as short as 1.5m high. But a 100 year old tea tree growing in the wild can also grow higher than 3m high. Eventually the government will legislate what classifies as "gu shu." Until then, let the buyer beware!“