key lock Cast Metal Puzzle from Hanayama Puzzles of Japan is both a delightful and tricky brain teaser puzzle. It consists of Two pieces which completely separate. The object is to disassemble and assemble back together. Measures approximately 1.25 inches across. This is a really fascinating disentanglement brainteaser. You may find yourself turning the center ball around and around for longer than you planned. Recommended for ages 12 to 105 years. Rated by the manufacturer as a level 4 difficulty (on a scale of 1 to 6 where 6 is the most challenging.) Difficulty level shown on the packaging. Your own experience could vary substantially. key lock is part of a series of 55 plus very interesting and mentally provocative metal brain teasers from the Hanayama Puzzle Company. Some serious puzzlers refer to these as "disentanglement-style puzzles" as they involve taking something apart and then re-assembling. Re-assembly can also be a puzzle and may be equally as tricky. Reminder. NO FORCE is ever required to solve the puzzle. Just a series of clever moves. Forcing pieces may damage the puzzle !!