From the ThinkGeek.com description:
Individually milled from a solid block of metal, the Revomaze features an internal labyrinth full of dead ends, traps, and one way paths you need to navigate to remove the metal core and solve the puzzle.
What makes the Revomaze truly great is its challenge to both your mental and physical aptitude. You need dexterity to manipulate the Revomaze as well as brain power to ferret out the correct path in the labyrinth. One wrong move and you're forced to start from the beginning. However the Revomaze is very fair minded... you screw up, you get punished, but you're always aware of whether you are making progress towards the solution.
Here's the link for the Revomaze mechanical puzzles.