Section 18 OPTICAL, PHOTOGRAPHIC, CINEMATOGRAPHIC, MEASURING, CHECKING, PRECISION , MEDICAL OR SURGICAL INSTRUMENTS AND APPARATUS; CLOCKS AND WATCHES; M USICAL INSTRUMENTS; PARTS AND ACCESSORIES THEREOF 91 Clocks and watches and parts thereof 91 12 Clock cases and cases of a similar type for other goods of this Chapter, and par Commodity Code Description 91 12 20 91 12 90