In the early 80's an unknown Hungarian professor launched a simple invention that captivated the world and spawned imitations. The sliding barrel puzzle was one of these and it became popular enough that you can still get them to this day. This mini version is a puzzle on a keyring that'll go everywhere you do. Whether it's a distraction you need, or something to pass the time for a while this will do the trick.
Consisting of three rotating barrels each of which has 6 slots containing a coloured tile. There is one gap which allows tiles to be moved one at a time to complete the puzzle similar to the square, 2D picture & number puzzles which have remained popular for centuries.
The puzzle is supplied in it's “solved” state so you'll need someone to “mess it up” for you first...It would be a bit too easy otherwise, don't you think?