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 WATCH CASES OF BASE METAL, WHETHER OR NOT GOLD-OR SILVER PLATED Commodity Code Description 91 11 20 00 WATCH CASES OF BASE METAL, WHETHER OR NOT GOLD-OR SILVER PLATED