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 31 Measuring or checking instruments, appliances and machines, nes 90 31 90 Parts and accessories of measuring/checking instruments, appliances and machines Commodity Code Description 90 31 90 00 Parts and accessories of measuring/checking instruments, appliances and machines