Perfect gift for the men in your life, buy the entire series for them to have fun for hours (not just on the toilet.) Serves purposefully as a bathroom book, make sure to include a pen! When the book is complete make sure to purchase the next from the series for them, as we know they will need something else to do! Great to stimulate your mans brain with this hard 16 x 16 Sudoku Puzzle Book. Help them become a Sudoku Pro by solving all 55 puzzles in this book. Be careful - Sudoku Books can be addictive, as can sitting on the toilet for hours at a time, but at least they will be mentally active instead of reading the back of the shampoo bottle over and over. With 55 puzzles included in this book, the mental stimulation will last for at least 30 days to a full year. Great pocket size 6" x 9" means it's the perfect size to serve as a bathroom book, travel book or travel restroom book. Feel free to work the brain anytime, anywhere! Quick Creative's Version of Extreme Sudoku Puzzle Book 55 HARD 16 x 16 Puzzles includes: 55 Hard Sudoku 16 x 16 puzzles Answer Pages Hours of Fun Solution Pages Larger Print One Puzzle Per Page Search the author name above for more extreme Sudoku Versions from Easy to Extra Hard and 9x9 or 16x16.