"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." -Bill Cutler
The length of the pieces must be 10 units for the disassembly to require 10 moves. With 8-units pieces, the maximum is 6 moves, and with 6-units pieces, no more than 5 moves are needed. Another way to enforce the level 10 solution among other possible assemblies is to add a dowel on a carefully chosen position on the side of each piece, so that they form two opposite groups when the puzzle is assembled.