The present invention relates to multimers of polypeptides which are covalently bound to molecular scaffolds such that two or more peptide loops are subtended between attachment points to the scaffold. The invention also describes the multimerization of polypeptides through various chemical linkers and hinges of various lengths and rigidity using different sites of attachments within polypeptides. In particular, the invention describes multimers of peptides which are high affinity binders and activators of CD137. The invention also includes drug conjugates comprising said peptides, conjugated to one or more effector and/or functional groups, to pharmaceutical compositions comprising said peptide ligands and drug conjugates and to the use of said peptide ligands and drug conjugates in preventing, suppressing or treating a disease or disorder mediated by CD137.