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 21 HEARING AIDS AND OTHER APPLIANCES WHICH ARE WORN OR CARRIED OR IMPLANTED 90 21 50 PACEMAKERS FOR STIMULATING HEART MUSCLES, EXCLUDING PARTS AND ACCESSORIES Commodity Code Description 90 21 50 00 PACEMAKERS FOR STIMULATING HEART MUSCLES, EXCLUDING PARTS AND ACCESSORIES