This is one of the most difficult packing problems that you"ll find. This crafted wooden brain teaser cube contains 25 identical Y shaped pieces. The objective is to build a 3X3X3 Cube, using all the pieces. You can also try building other rectangles shapes by using part of the pieces. It comes with a nice looking base and a lid for keeping the pieces all together. Consider to be one of the hardest cubes ever.