4/4 Full color on both sides of the sheet. This option can reproduce the range of colors you see in a typical photograph out of the standard 4 printing colors: cyan, magenta, yellow, and black. Typical examples of this are magazine covers and high-end catalogs. 4/1 Full color (cyan, magenta, yellow, and black as above) on the front and black on the back. A typical example of this is a flyer. 4/0 Full color (cyan, magenta, yellow, and black as above) on the front and no printing on the back. A typical example of this is a poster.