Tenyo Pentomino Square Brain Block - A puzzle you can play forever! Difficulty Level 4, for intermediate to advanced players. Total of 16,146 solutions. Brain exercise. TBB-04. Just taking the pieces out and putting them back in the case is incredibly difficult. Product Dimensions: 14.6 cm length x 17.2 cm width Theme: Video Games Difficulty: 4 (16,146 solutions) Target Age: 6 years and up Size: 15 x 1 x 17 cm No price reduction.