Fluorescent red Mega 520 and other Mega dyes are specifically designed for multicolor techniques. It is characterized by an extremely large stokes shift between excitation and emission maxima. This dye is especially well suited for excitation by argon lasers or other short wavelength excitation light. This also means that it can be excited with the same light source or filter arrangement as fluorescein and other widely used dyes, as well as other Mega dyes. Due to the different emission wavelengths several different labels can be detected independently in the same experiment. Due to the small size of the Mega labels and the direct conversion of excitation light into emission without using a FRET mechanism, there is a variety of possible applications including DNA sequencing and FISH microscopy.