Sketch in full colour. 4 colour ball point penIncludes the colours Cyan, Magenta, Yellow and BlackCan be used to create every colour by combining the 4Includes a mixing guide on packet Every colour can be created by combining the 4 colours; Cyan, Magenta, Yellow & Black. The CMYK process is used in printing to build up full colour images, and now you can use that same process to create full colour