This is another nice looking aluminium puzzle from Eureka, and it is called Prison Block:
I do like the look of this one, which is probably what drew me to it in the first place. It has a good weight to it as it is entirely constructed from aluminium. There are two primary pieces to this puzzle, and they are the silver colour frame and the black central rectangular block with the purple block attached to it.
The goal is to remove the black and purple central piece from the aluminium frame. The central piece will rattle around quite freely within the frame but it seems physically impossible to make it pass through. If you pay really close attention to the two pieces then you won't have too much difficulty solving it, however I did hand it around at a puzzle gathering today and many people there were unable to do so.
I think it took me approximately 10 minutes or so to solve Prison Block, which is a pretty decent amount of time, but I reckon it could easily take longer with puzzlers who are not too familiar with these types of puzzles.
I got hold of this puzzle from Sloyd in Finland, and I honestly cannot praise them enough. I recieved my order from them two days after I ordered it, and that's including the international post!