The TaKaRa DAB Substrate includes reagents needed to prepare DAB (3,3’ -diaminobenzidine tetrahydrochloride salt) solution, a substrate of horseradish peroxidase (HRP). DAB develops a dark brown-colored product upon reaction with HRP, and therefore can be used to visualize where peroxidase-conjugated antibodies bind to a sample. DAB is used in immunohistochemical staining and can also be used to stain other materials, including fixed cells and nitrocellulose membranes.