Dr. Oskar van Deventer, from the Netherlands was born in 1965 and started designing puzzles as young as 12 years old. He designs puzzles as a hobby and is a senior scientist working on network and answering control. He designed this puzzle and it was manufactured by Hanayama in 2006. Dr. van Deventer has designed hundreds of puzzles, winning prizes internationally. He has a very interesting Website showing many of his puzzles, it’s well worth visiting.
The Cast Duet is one of the most difficult in the Hanayama collection. Hanayama gives it a Difficulty Rating of 5 of 6, Puzzle Master rate it 9 of 10. Like all Hanayama puzzles, it is of excellent quality, made of heavy cast metal, with polished gold and silver finishes.
There are grooves on every square and the rings. The ring can be split and has magnets to hold it together. The object is to separate the ring and remove each half.
Also, at each corner of the center ring, there are 4 triangles with 1, 2, 3 or 4 dots. For further challenges get the ring to go through the 2 squares at the base of the triangles (center side, not corner squares). The challenge increases as you go from 1 dot through to 4 dots. This is a great puzzle as it can be played with over and over again.
You can purchase this puzzle and get the solution at Puzzle Master.