Made from strong and durable nickel plated wire, the Keyhole puzzle keeps a secret hidden that you need to learn. To do that, you must be able to remove the string from the frame, which won’t be an easy task. A very original design and one of our toughest puzzles. Only for courageous puzzlers. The Keyhole is from our wide selection of PuzzleMaster Wire Puzzles and it comes in a reusable clam shell packaging.