This may be the biggest book of chess challenges, it certainly is not the best. I really don't see the point of more than 50 pages with mates in one, more than 650 pages with mates in two, and more than 100 pages with mates in three. It is certainly good to practice tactics and having a decent collection of mates is very useful, but this is ridiculous. What about all these other combinations; pins, skewers, forks, etc. etc.? Contrary to what the product description wants you to believe the book does not cover a complete range of levels to build chess skills. Let alone that it contains every known checkmate position. The endgame part is more useful, but that part has only 30 pages. If you want to improve your tactics buy Thousand and One Winning Chess Sacrifices and Combinations by Fred Reinfeld or his 1001 Brilliant Ways to Checkmate if you want to restrict yourself to mates. These books are also much easier to carry around.