This is an original B4 music score case from DAC. It has been opened, but is unused. [From the DAC official page] The popular music score case has been slightly updated! It's now large enough to hold B4-size clear files! Furthermore, the direction of the zipper that opens on three sides has been changed, allowing you to take out the contents from either long side! Inside, there are two pen holders. It can be attached to the DAC original trombone case NX-1s, trumpet case TP2+, clarinet 3WAY double case, and euphonium case e-Case (using the included adjuster) at the four points where the backpack straps are attached. In the case of the clarinet 3WAY double case, it is attached to the gap in the strap金具. When attached and worn on your back, it will be between the case and your back, which also increases the cushioning!