The newest and most challenging PolyPack puzzle, Two new pieces provide additional packing schemes and puzzle challenges that will hold students" interest, Combined with previous PolyPack puzzles, this manipulative yields even more interesting variations on packing a cube space with polyhedra, With the same specific gravity feature as PolyPackPlus puzzle, The PowerPack has 18 pieces in a clear plastic cube, With activities, SKU: SKPBG015