The Perfect Protein™ Western Markers consist of seven recombinant S•Tag™/His•Tag® fusion proteins that can be detected on any Western blot using an S-protein AP or HRP conjugate. As an additional option, the markers can also be detected with an His•Tag Monoclonal Antibody and an AP or HRP conjugated secondary antibody. The Perfect Protein Western Markers serve as precise size standards that appear simultaneously on the blot with target proteins, eliminating the uncertainty and imprecision associated with other methods.