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, not specified or included elsewhere in this Chapter; profile projectors. Commodity Code Description 90 31 10 Machines for balancing mechanical parts 90 31 20 Test benches 90 31 41 For inspecting semiconductor wafers or devices, photomasks or reticles used in..., 90 31 49 Other 90 31 80 Other instruments, appliances machines 90 31 90 Parts and accessories