Tandem dyes are a unique class of fluorescent molecules that consist of two different covalently linked fluorophores, a donor (e.g. PE or APC) and a longer-wavelength emitting fluorescence acceptor (e.g. Texas Red, Cy5, Cy7, iFluor® 594 or iFluor® 750). APC-iFluor® 770 is a new unique tandem color for multicolor applications, in particular, for designing spectral flow cytometric panels. It has been validated with Cytek’s Aurora flow cytometer. Its primary absorption peak is at 651 nm with emission peak at ~803 nm. It is one of the brightest NIR fluorophores that can be used with flow cytometry and fluorescence imaging applications.