This is a Kuman German language textbook binder. You can close and store Kumon worksheets. The thickness can be adjusted for 200 sheets or 400 sheets. The string may be black. When you start learning, it's difficult to keep a huge amount of worksheets, but it's hard to throw them away... so you can file and keep them for each textbook. For those who have progressed, their solved textbooks will be the best reference books, so filing them by textbook is a great way to remember old grammar when you don't understand something. It fits exactly 200 or 400 sheets and doesn't create wasted space. Easy to put on a bookshelf. Material: Paper Please also take a look at ↓ #Kumon related, children's enjoyable collection If you have any questions, please feel free to comment.