A4 Hardcover exercise books come in various thicknesses measured by the number of quires they contain. A quire refers to a traditional unit of paper quantity, typically consisting of 24 or 25 sheets of paper folded together. Here's a quick description of hardcover exercise books in 1 quire, 2 quire, 3 quire and 4 quire formats:

The A4 3 quire hardcover exercise book contains three quires of paper, totaling approximately 72 to 75 sheets, enclosed within a sturdy hardcover binding. These offer even more space and thickness compared to 1 or 2 quire books and are suitable for extensive note-taking or maintaining detailed records over an extended period.