Leuchtturm1917 make amazing durable and beautiful notebooks, and this sketchbook is no exception. It is the perfect balance of form and function; small enough to carry around with you and big enough to satisfy even the most avid of sketches. As with all Leuchtturm notebooks, it has that very handy expandable pocket at the back for keeping notes, mementos or your bits of stationery. It's thread-bound, which means it opens flat so you can draw right to the edge of the paper. The paper is acid free, to preserve your masterpieces forever!! The square size makes this sketchbook incredibly versatile and perfect for sketching, taking notes, or any combination. The paper is ideal for ink, charcoal, chalk, paints, and a variety of media.  What size is it?22.5 x 22. 5 x 3 cm.