Hanayama O'Gear cast metal brain teaser puzzle

The object of the O'Gear Cast Brain Teaser Puzzle is to remove the 5-pronged gear from the square box, then replace the gear into box so that gear tooth with hole (not shown here) is inside the box. Rated as a 'medium' level of difficulty.

From the puzzle description

First developed in 19th century Britain, this die-cast zinc cube and key is an ancient puzzle that still baffles minds today. A prizewinner from the 2001 1st Annual World Puzzle Design competition, this puzzle was designed by the young Dutch phenomenon, Oskar, consider to be one of the world's brightest creators. The gear exhibits a unique kind of movement. Once together in its final form of beauty, the gear fixed in place in the cubic box could very well serve as a desk decoration to satisfy a kind of soothing, intellectual curiosity.

Here is a link to the Cast O'Gear Puzzle

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