The PreSafeStain 6X DNA Loading Dye for running DNA samples on an agarose gel. It contains two regular tracking dyes and a safe, non-carcinogen green fluorescent dye. The two regular dyes are for monitoring the agarose gel while it is running, and the green fluorescent dye is to replace the toxic carcinogen ethidium bromide (EtBr). By using this special DNA loading dye, your agarose gel will reveal two different colors, blue and yellow, while running. The gel can be directly visualized under LED light or UV light without any extra staining steps. DNA stained with the fluorescent dye will emit a green light (530nm).