DAB Chromogen kit consists of two components – DAB Concentrate and DAB Substrate. DAB, that is, 3,3′-diaminobenzidine is a chromogen most frequently used for visualizing antibody reaction with antigen during immunohistochemical staining. It is used with samples fixed using formalin or glyoxal and embedded in paraffin. Along with the presence of the peroxidase enzyme, at the location of the antigen, it forms a brown precipitate that is not soluble in alcohol and xylene. The signal is clearly visible with hematoxylin counterstaining. The working solution is stable for up to 6 hours at room temperature, or up to 14 days at 4°C. The stained preparation is stable after mounting with a BioGnost mounting medium.