Nearly identical in appearance to Brass Monkey One, Two, and Three, Brass Monkey Four has yet again upped the difficulty. Steve and Ali's continued innovation has created a monster puzzle that is perfect for fooling those who think they have seen it before. Brass Monkey 4 looks like a standard interlocking Burr. It isn't! The subtle differences on the end of its pieces compared to its predecessors belie the additional complexity hiding within. Like the first few puzzles, it weighs almost 800g (1.1 lbs). Each piece is 70mm long and has a diameter of 19mm.