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, PHOTOGRAGHIC, CINEMATOGRAPHIC, MEASURING, CHECKING, PRECISION, MEDICAL OR SURGICAL INSTRUMENTS AND APPARATUS; CLOCKS AND WATCHES; MUSICAL INSTRUMENTS; PARTS AND ACCESSORIES THEREOF 90 31 MEASURING OR CHECKING INSTRUMENTS, APPLIANCES AND MACHINES, 90 31 90 PARTS AND ACCESSORIES FOR MEASURING/CHECKING INST./APPL. & MACH., N.E.S... Commodity Code Description 90 31 90 00 PARTS AND ACCESSORIES FOR MEASURING/CHECKING INST./APPL. & MACH., N.E.S...