|It takes 10 moves to remove the first piece of the puzzle.
This is the largest number of moves for any notchable
6-piece burr with internal holes and otherwise normal cuts.
The design was found during an exhaustive analysis of the
13,354,991 different notchable 6-piece burrs. The analysis
was run using computer programs written by Bill Cutler and
took over two months to complete.
The pieces can be put together in many ways to form a 6-piece
burr, but only one of them is the desired level-10 solution. This
solution is 'enforced' by the diagonal lines marked on the pieces.
When the pieces are assembled into the correct level-10 solution,
the lines connect to form a 'rubber-band' marking around the puzzle.
If you prefer to have a model without the black markings,
subtract $5 from the price.