The present disclosure relates to a multi-specific antibody molecule comprising or consisting of three polypeptides: a) a polypeptide chain of formula (I): (Vxx)nVx-Cx-X-V1; and b) a polypeptide chain of formula (II): (Vyy)nVy-Cy c) a polypeptide of formula (III): V2 wherein Vx represents a variable domain, Vxx represents a variable domain, Cx represents a constant region, X represents a linker, V represents a variable domain, Vy represents a variable domain, Vyy represents a variable domain, Cy represents a constant region, V2 represents a variable domain, n independently represents 0 or 1, wherein the polypeptide chain of formula (I) and the polypeptide chain of formula (II) is aligned such that the constant regions Cx and Cy are paired and the variable domains Vx and Vy are paired to form a binding domain and optionally a disulphide bond is present between V and V2, in particular where a disulphide bond is present. The disclosure also extends to pharmaceutical formulation comprising the construct, DNA encoding the constructs and vectors comprising same. The disclosure further extends to a method of expressing the constructs, for example in a host cell and methods for formulating same as a pharmaceutical composition. The disclosure also relates to use of the constructs and formulations in treatment.