CF® Dye Succinimidyl Esters (SE), also known as N-hydroxysuccinimide (NHS) esters are amine-reactive fluorescent dyes. They are commonly used to label primary amines of antibodies and other proteins, amine-modified oligonucleotides and other amine-containing molecules.

CF® Dye Maleimides are thiol-reactive fluorescent dyes. Maleimides are commonly used to label proteins, peptides or other molecules containing free thiol groups.