Music Folder: Used to store sheet music, documents, etc., music folder, clef, A4 paper with 30 compartments. Material: The inner pockets are non-slip and transparent with high-quality polypropylene (PP). The spiral binding allows the binder to be opened at a 180-degree angle for flat sheet music. WATERPROOF & THICK POCKETS The inner pockets are non-slip and transparent, and the concave-convex technology can reduce the reflected light to ensure that your sheet music does not get wet when practicing. PERFECT FOR: Suitable for daily filing and storage of A4-sized documents and smaller than A4, widely used in offices, schools and households. Works equally well on piano, organ or performance synthesizer. Easy to use: choir and piano sheet music and other papers can be inserted. A standard display book that can be easily inserted and removed from the sheet music or files.