Design is the world's leading puzzle Dr, Nobuyuki yoshigahara. 6 (highest difficulty) and led to public determine the degree of difficulty during development planning has been made.　 "The cause" and is? "Has caused" and the adult inspiration and logic to solve the puzzle. The Mission's "off." And "back to you". Simple, but profound. And take full advantage of the head and hands, I try to challenge you. Product specifications: ages: 6-year-old-difficulty: 6 (out of 6) size: 75 × 119 × 45 (mm) weight: 142 g