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 32 Automatic regulating or controlling instruments and apparatus 90 32 81 Hydraulic or pneumatic 90 32 81 00 Hydraulic or pneumatic Commodity Code Description 90 32 81 00 000 Hydraulic or pneumatic