Designed by Jean Claude Constantin this puzzle is called Lock 250 because there are 250 moves to open... that means another 250 moves to close again. And that's only if you get them all correct!
The 4 steel sliders on the front move the internal wooden plates of the puzzles and which slider you can move depends on the position of the internal plates. It may not look like it at first but actually the Lock 250 is in the same family as the Chinese Ring puzzle and others classified as n-ary puzzles. Where the Chinese Ring puzzle is a binary puzzle, moves have 2 states, the Lock 250 has 5 states quinary puzzle.
Size: 98mm x 145mm x 30mm The puzzle is made from laser cut plywood and the outside is veneered.
No solution provided.
To read an interesting review that compares this puzzle to its HUGE big brother "Generation Lock" (also available here at Mr Puzzle!) go to Puzzling Times Blog.