Thank you for viewing. The blue one is unused and has been stored. The pink one has been used, but it's relatively clean. The inner diameter of the ring is about 8mm, and the maximum capacity is 20 sheets. (The blue one is a set of 20 sheets, the pink one has 12 sheets that haven't been separated and 2 sheets that have.) This is a rare type of vocabulary notebook where the pages can be separated (please refer to the photos. A few pages have been separated, but most are still in their original state). It seems to be discontinued, so if you are looking for this type of vocabulary notebook, please consider it.