a) knobs-into-hole bispecific antibody, like it is used in the Duobody™ format, b) globular domain proteins fused to IgGs, e.g. FynomAbs™, c) double-variable-domains Immunoglobulins (DVD-IgGs™), d) Bispecific T Cell Engager (BiTE™), e) single-chain diabody (scDb), f) Tribody, g) DART™, h) chemical cross-linking of two Fab fragments, i) TandAb™. Constant regions indicated in grey, VH1 indicated in dark blue, VL1 in light blue, VH2 in dark green and VL2 in light green. Globular domain proteins indicated as dark green hexagons.