12 pieces with inlaid letters. Pieces with tongue and groove. All pieces 20x20 mmSlide from the starting position ALBWHITE CK!!ET TO !WHITE !BLACK! On the back there is a slide up and down. This slide changes the free hole.Then slide to BLACK! WHITE! easy?Material Acrylic.
All numbers are in a slide.Slides from left to right. Under number 4 is the free hole. A difficult puzzle, but it can be solved. Assignments on the back of the puzzle.Material acrylic.
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