There are different Inside³ Phantom 3D Labyrinth Puzzle Cubes - each one more challenging than the last.
Inside each cube are seven levels, each a labyrinth. You must turn the Inside³ 3D Labyrinth Puzzle Cube, blindly manipulating the 2 balls through each level of maze to get it to be visible on other side.
This listing is for the newer Phantom Cthulhu. Unlike the Inside3 original series, the Phantom cube has 2 balls to manipulate through the maze. What makes it much harder to solve, and this black version also cannot be opened.
If you want to see the balls come out at the back, you will need extreme patience, some luck and no lack of skill. Either that or a hammer :).