http://www.cd-bioparticles.com/p/Streptavidin-Magnetic-Particles_20_194_237_273.htmlAbsolute Mag™ Streptavidin Magnetic Particles, 4.0-4.5 μm (# WHM-S107) are magnetic beads coated with streptavidin covalently. Due to their high affinity binding to biotin, they have found widespread use as detection reagents in immunology, nucleic acid isolation, protein purification, and cell separations.DNA/RNA Purification, Antibody/Protein Purification, Immunoassay, Cell Isolation