Section 18 Optical, photographic, cinematographic, measuring, checking, precision, medical or surgical instruments and apparatus; clocks and watches; musical instruments; parts and accessories thereof 90 Optical, photographic, cinematographic, measuring, checking, precision, medical or surgical instruments and apparatus; parts and accessories thereof 90 26 Instruments/apparatus for measuring the flow... of liquid or gases, nes 90 26 20 For measuring or checking pressures 90 26 20 00 For measuring or checking pressures Commodity Code Description 90 26 20 00 000 For measuring or checking pressures