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.
Copy produced by puzzle design Ton Delsing.F. D. The world famous Initials. Frank Delano Roosevelt's Initials.Registered U.S. Patent Office.The F consisted of 5 red pieces, the D of 6 blue pieces.Material. Thin Plastic.