6-HEX NA NHS ester is a pink fluorescent dye producing a stable fluorescent signal in bioimaging. Optical properties of 6-HEX NA are similar to that of HEX, JOE, VIC and Cal Fluor 560. The excitation and emission maxima of 6-HEX are at 534/549 nm. NHS esters readily react with amino groups of biomolecules such as the ε-amino group of lysine or the amine termini of modified nucleotides to form stable amide bonds between dyes and biomolecules. We offer 6-HEX NA NHS ester for labeling biomolecules and amino-modified oligonucleotides in solid phase oligonucleotide synthesis.