For most oolong teas, the fragrance begins to dissipate the minute you open the container, but contact with air enhances the fragrance of pu'er tea. Thus the interior bag holding the tea leaves is made of tissue paper, which can breathe.
一般烏龍茶只要一開封，香氣就會散逸，但普洱不同，必須接觸空氣、愈陳愈香，所以「御奉」內裝的普洱，就用「可以呼吸」的棉紙包覆。