Volume 2 - 320 Sudoku Puzzles. - Difficulty Level is very Medium to Very Hard. - 4 puzzles per page with space to write. - Great way to boost your memory, focus and concentration. - Encourages logical thinking and teaches patience. - Improves problem solving skills. - Solutions included at the back of the book. - Dimensions: 5.5 X 8.5 Inches (21.59 cm x 27.94 cm – A5 Size)