Special Notice: DEPT OF DEFENSE, DEPT OF THE AIR FORCE is procuring LIQUID AND GAS FLOW, LIQUID LEVEL, AND MECHANICAL MOTION MEASURING INSTRUMENTS (PSC code: 6680). These instruments are typically used for measuring and monitoring the flow of liquids and gases, as well as the level of liquids. The specific item being procured is identified by the National Stock Number (NSN) 6680-01-039-7817.