Hobonichi Blank Notebook - A5 SizeBlank Notebook Details This A5 size notebook has thin and sturdy Tomoe River paper and opens flat. You can use this notebook with extra freedom to draw pictures or brainstorm designs. The notebook is 10mm thick and contains 288 pages so you can write as much as you want in a single book. It's the same size as the techo, so it can fit into a techo cover. The notebook size is the same as the A5 Cousin, which makes it compatible with any of the Cousins