CaptureSelect products contain affinity ligands based on recombinant single-domain antibody fragments (VHH) created by a proprietary technology. The VHH affinity ligand is a 12 to 15 kDa fragment comprising the three complementarity-determining regions (CDRs) that form the antigen-binding domain, efficiently produced in the yeast Saccharomyces cerevisiae by a production process free of any animal components (Animal Origin-Free).