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. Graph paper 5x5 mm - Pack of 25 books. Packing unit: 25 books, 36 pages, portrait format, A4 (8.27x11.69 inch), graph paper 5x5 mm (0.2x0.2 inch), cover blue.