The HKS is a colour system which contains 120 spot colours and 3520 tones for coated and uncoated paper. HKS is an abbreviation of three German colour manufacturers: Hostmann-Steinberg Druckfarben, Kast + Ehinger Druckfarben, and H. Schmincke & Co. The association of those three companies have defined the colours of the HKS system since 1968.