Built to very tight tolerances with very fine sharp edges, the quality and construction is excellent throughout. Careful handling is needed for this one.
Only 4 irregular shaped pieces, this is a level 9.3 interlocking burr. In terms of difficulty, not difficult, especially if you are familiar with some of William Hu's other puzzles such as the Ring Lock. You will probably figure out quite quickly how and what needs to be done. For the uninitiated, may pose a serious challenge tho'