Medical Laboratory Scientist (MLS) Caduceus Pin. MLS is proudly stated in black enamel on this 3D gold plated Caduceus. The caduceus is frequently used by the medical field, military medics and has become the unofficial symbol of medical professionals. These pins are perfect for a graduation presentation, as a gift for your MLS team or for a medical conference! Each caduceus pin includes a clutch back and is individually poly bagged.