A very effective demonstartion that white is composed of 7 colors of the spectrum. Consists of a 9" dia. wheel with four quadrants of the seven colors of the spectrum in wedges of violet, indigo, blue, green, yellow, orange and red. When the wheel is set in motion they blend together giving a simulation of white light. A black plastic handle attaches to the center of the wheel on the back side, which already has a mounted pulley, which can be spun with an included cord. Kit included, the color wheel, handle and cord on spool.