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 24 MACHINES AND APPLIANCES FOR TESTING THE HARDNESS, STRENGTH, 90 24 90 PARTS AND ACCESSORIES OF MACHINES & APPLIANCES FOR TESTING THE HARDNESS... 90 24 90 00 PARTS AND ACCESSORIES OF MACHINES & APPLIANCES FOR TESTING THE HARDNESS... Commodity Code Description 90 24 90 00 000 PARTS AND ACCESSORIES OF MACHINES & APPLIANCES FOR TESTING THE HARDNESS...