Section 16 MACHINERY AND MECHANICAL APPLIANCES; ELECTRICAL EQUIPMENT; PARTS THEREOF; SOUND RECORDERS AND REPRODUCERS, TELEVISION IMAGE AND SOUND RECORDERS AND REPRODUCERS AND PARTS AND ACCESSORIES OF SUCH ARTICLES 84 NUCLEAR REACTORS, BOILERS, MACHINERY AND MECHANICAL APPLIANCES; PARTS THEREOF 84 83 AND SHAFT COUPLINGS (INCLUDING UNIVERSAL JOINTS). 84 83 90 MILL CHAIN SPROCKETS FOR AIRCRAFT ENGINES 84 83 90 31 MILL CHAIN SPROCKETS FOR AIRCRAFT ENGINES Commodity Code Description 84 83 90 31 000 MILL CHAIN SPROCKETS FOR AIRCRAFT ENGINES