Generally, goat anti-human or donkey anti-human IgG polyclonal antibodies are used as the secondary antibodies to detect human IgG (H+L). However, since polyclonal antibodies can recognize many epitopes, the background and the cross reactivity in assays is usually high, making results hard to interpret. As a mouse monoclonal antibody, the unique GenScript Mouse Anti-Human IgG Fab Antibody (12H3C4A6)[HRP], mAb has a high specificity to the human IgG Fab portion and can be used to detect human antibodies which include the human IgG Fab portion.