Binary Key II is Pit Khiam Goh's two-dimensional interpretation of Bill Cutler's excellent "Binary Burr." The goal is to remove the bottom key from the frame by manipulating the internally sliding pieces. The solution requires 85 moves and is non-trivial.

Pit Khiam's description: "Binary Key II is a redesign of my Key Puzzle. The original puzzle was minimalist by design, but I felt some pieces could be changed to make them slide better. The key piece is now made shorter, and the number of rings has been increased to 5 instead of 4. The number of rings can be increased indefinitely due to the relation between the number of rings n and the number of moves Tn to solve the puzzle."

This is our first release of both Binary Key II and Tern Key since 2013. For this release we have modified the design with slightly thinner extruded acrylic middle and top layers for better operation. We also added a thin spacer layer to ensure smooth internal movement, and replaced the metal key pins with acrylic for more reliable press fitting and retention.

Precision cut from solid acrylic and painstakingly hand-assembled, Binary Key II has a nice weight and feel. It will not be confused with cheaper mass-produced take apart puzzles! Construction uses contrasting press-fit dowel pins to align the internals.

is an excellent blog review of Binary Key II. Another review of both Binary Key II and Tern Key may be found .

Pair this with for an ideal sample of grey-code style puzzles in your collection!

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