Stainless steel rings, the inside features a transparent interlayer design, suitable for A4 size, both positive and negative sides can be used, suitable for up to 30 pages. The humanized design allows for convenient use. The accessibility between the membrane and the middle allows you to change the contents as you wish. High-quality polypropylene (PP) (non-toxic and non-radioactive). Durable and stylish. 32 x 25 x 2 cm (approximately). Adjust the folder. Perfect for all instruments and musicians. An excellent choice for music lovers. Product Color: Black Unique appearance with a high-quality feel. With its creative, multi-layered A4 design that is hollowed out in the middle, it is the perfect choice for music lovers. The portfolio can be used on a variety of musical instruments and occasions. Suitable for daily filing and storage of documents, sheet music, etc.