DAB (3,3'-diaminobenzidine) reacts with HRP in the presence of peroxide to yield an insoluble brown-colored product at locations where peroxidase-conjugated antibodies are bound to samples. The brown precipitate is insoluble in alcohol and other organic solvents, making it an excellent substrate for immunohistochemical staining that requires the use of traditional counterstains and mounting media. The DAB substrate kit includes 20X DAB substrate solution and 20X stabilized peroxide buffer, 15 mL each.