Tandem Fabs are a class of Fab-based bispecific antibody fragments. Just as its name implies, tandem Fab comprises two Fabs targeting different epitopes. Usually, Fab is more thermally stable than the corresponding scFv. Usually it is expressed as a 3-chain construct and has a His-tag for affinity purification. The two Fd regions are connected by a flexible linker. Tandem Fab is bispecific and has monovalent for each antigen specificity (1+1 antigen-binding valency).