The puzzle is a set similar to the Penultimate Burr with multiple problems to be solved. The set consists of a 4×4×4 cage with a 2×2 opening on each face and 14 non-planar penta/tetracubes. The objective is to fill the cage with four of the pentacubes and three tetracubes to complete a 4×4 cube. A jig is provided for testing possible solutions outside the cage, as well as a box which doubles as a display plinth for the solved puzzle. This is a difficult puzzle, with two assemblies having a unique sixteen move solution!