The object of the puzzle is to remove the washer from the bolt. To do this, the only obvious way is to remove the nut. The nut is also not your run-of-the-mill version as it has what appears to be a rod running through the side.
Unlike the typical bolt and nut puzzles, this one is a sequential discovery puzzle; meaning that you have to follow a number of steps in sequence with the aid of certain tools that come with the puzzle which you first need to discover.
From my perspective, there are 6-7 steps (depending on how you count) to getting the washer out. While not overly difficult, the puzzle does provide a good amount of challenge. I managed to solve mine within 15-20 minutes. The trick of the mechanism in the puzzle although pretty simple once you see it, is actually quite clever.
Overall a very nice bolt and nut puzzle with a slightly different twist. For puzzlers who like nut/bolt/washer or sequential discovery puzzles, this is a gem and definitely worth acquiring. Available directly from Wil Strijbos.