NanoTag's Selector resins are based on high-affinity single-domain antibody (sdAb) fragments covalently immobilized on 4% cross-linked agarose beads. The innovative, oriented and selective attachment via flexible linkers guarantees optimal accessibility of the sdAbs and in addition largely eliminates batch-to-batch variations. Due to the single-chain nature of sdAbs and their stable and covalent attachment, no leakage of light and heavy chains is observed during elution with SDS sample buffer. Selector resins thus feature high affinity and superior capacity for fusion proteins while showing negligible non-specific background. Selector resins are compatible not only with physiological buffers but also with high stringency buffers (see product-specific compatibility charts) and reducing agents. Selector resins thus provide great freedom to adjust the binding and washing conditions to the experimental needs.