This is perhaps the world's oldest puzzle. It is attributed to Archimedes of Greece (287 BC – 212 BC). Difficult to solve, with fourteen precision cut 1/4" thick acrylic pieces. The point is to arrange all the pieces to fit inside the square frame. Mathematician Bill Cutler determined in 2003 that there are 536 totally distinct ways to assemble the square shape. Yet it is extremely difficult to find even one. There are many websites that contain fascinating historical and mathematical information about this game. Level 5 difficulty. The frame with cover measures 7-1/2" x 7-1/2". Challenge yourself. Made in the U.S.A.