These books are made with a lighter weight 150 gsm (40 lb.) card stock cover. They are filled with high quality 80 gsm (20 lb.) paper, and are chlorine-free. These books are not available with onion skin page separators.Pack of 25 books. Pack of 25 books, 36 pages, portrait format, A4 (8.27x11.69 inch), graph paper 10x10 mm (0.4x0.4 inch), cover blue.