fADL-display is a type 3 phage display vector with a cloning site on the N-terminal side of the full-length gene III protein. Secretion in the periplasm of the fusion protein is driven by the PelB leader peptide, in place of the wild-type gene III protein leader sequence. fADL-1 derives from the phage vector fd-kan, a vector analogous to fd-tet where the tetracycline resistance genes derived from Tn10 have been replaced by the kanamycin resistance determinant of Tn903. Display is usually highly multivalent with limited polyphage production, even in the case of large polypeptides such as scFvs. This is the recommended format for peptide libraries which will benefit of the overall improved avidity.