Forenstix-Sero provide a fast and easy presumptive test for blood. Each Forenstix-Sero consists of a stiff plastic strip with an absorptive patch on one end that contains the test reagents. This test is based upon the pseudoperoxidase action of hemoglobin which catalyzes the reaction of Tetramethyl-benzedine and organic peroxide. The patch will turn a dark blue color when the water moistened patched end is rubbed onto a stain that contains blood. The patched end can also be rubbed on a dry stain and then add a drop of water. Although not as sensitive or specific as the Phenolphthalein, Forenstix-Blood, or O-Tolidine, Forenstix-Sero provide an additional alternative to these tests. Forenstix-Sero come in a vial of 100 tests. Does not affect subsequent DNA analysis.