Eight beautiful colors for hard-to-dye protein fibers like wool, mohair, feathers and more. The colors have been specifically selected for their colorfastness and affinity for wool fibers. Unlike typical acid dyes, Super Fast Acid Dyes are premetallized (also known as “metal-complex dyes”). Premetallized dyes strike faster than any other dyes and are regarded as having maximum washfastness and lightfastness.