Specifications: This instrument is used for the study of the frequency of images so that it seems that the picture is really moving. This happens because the speed of the rotation of pictures makes a reflection in the mirror, so that the optic nerves remembers the picture being spun, so that it seems that the picture is really moving. This set includes 12 mirrors is of size 21.5x7 cm which makes a cylindrical Dodecagon (12-sided) which has a diameter of 50 cm and is 15 cm in height. It has a rectangular base of size 52x52 cm. 100cm in height. The structure is made of wood covered with Formica plastic.