Section 18 Optical, photographic, cinematographic, measuring, checking, precision, medical or surgical instruments and apparatus; clocks and watches; musical instruments; parts and accessories thereof 91 Clocks and watches and parts thereof 91 11 Watch cases and parts thereof 91 11 20 Cases of base metal, whether or not gold or silver-plated Commodity Code Description 91 11 20 00 Cases of base metal, whether or not gold or silver-plated
