Accessory of Chinese traditional musical instrument Dizi 笛子. The film/mandrane is made from natural material, the inside surface of reed. The sound of reed film is different from those made by artificial material.
Each bag contains 5 pieces. The photo has one piece less because I photoed my used one, the sold ones are new and unopened. I usually split every piece into 6, and change the film every 1-2 weeks.
If you need the glue, let me know. The black glue in the photo is donkey-hide geltatin 阿胶. A single one is 1 pound. If you buy 3 bags of flim, you can ask me for a glue for free. Can ask me for guidance of use.