The Medical Instrument and Supply Set Case No. 3 was used by Army Medics and Navy Corpsmen1 to carry a variety of first aid equipment. Made from cotton duck, it contained three compartments, each of which had a zip closure. The bag was also equipped with a detachable carrying strap and was closed with a lift-the-dot fastener.Navy Corpsmen serving with Marine Corps units in Vietnam typically called the Medical Instrument and Supply Set Case No. 3 a 'unit one' bag.