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 24 Machines/appliances for testing the hardness, strength... of material 90 24 10 Machines and appliances for testing metals Commodity Code Description 90 24 10 00 Machines and appliances for testing metals