Check the sample puzzle on the back cover to judge the difficulty level. The puzzles in this book needs advanced Sudoku strategies to solve. X-Wing, Simple Colouring, Y-Wing, Swordfish, XYZ Wing This large-print 8.5" x 11" book is great for those who love large-print font for easy visibility. There are two diabolical level puzzles on each page and the solutions are included in the back of the book. Two big puzzles on each page give you plenty of space to note candidates and the sturdy paper holds up well to erasing. Large inside margins make it easier to solve the puzzles when you fold or tear out the pages. Great for sharing! Large print on white paper is very easy to read (even in dim light). The puzzles are for those that find newspaper Sudoku too easy. Use the sample on the back cover to judge if the level is right for you.