The performer shows a square made of metal strips which instantly changes to a circle. Then in a flash it is back to a square.
This is a flash magic item, and one which has been featured by several great magicians in their introductory quickies, because of the visual impact. “Squaring the Circle” is a mathematical impossibility, but for the magician nothing is impossible.
The apparatus is made from Stainless Steel material, and comes to you ready to use, complete with instructions.