OXYGEN, THERMAL CONDUCTIVITY, HYDROCARBON, NEAR INFRA-RED, PHOTOMETRIC, AND FLUE GAS ANALYZERS; OXYGEN DETECTORS; AIRCRAFT NAVIGATION INSTRUMENTS-NAMELY, [ VERTICAL SPEEDOMETERS, ANGLE INSTRUMENTATION, ] DIGITAL CONTROLLERS AND MINI-COMPUTERS, RECORDERS, SENSORS AND COLOR SHADE SENSORS; [ GUNSIGHT CAMERAS AND UNDERWATER MOTION PICTURE CAMERAS; PHOTOGRAPHIC ACCESSORIES-NAMELY, LENSES, CAMERA MOUNTS, ] PROTECTIVE HOUSINGS AND TRIPODS; POWER TRANSFORMERS; TRANSPONDERS, RADIO AND RADAR TEST SETS AND INTERROGATOR TEST SETS; [ DENTAL CASTING MACHINES AND DENTAL LATHES FOR LABORATORY USE; ] AMPLIFIER INPUT UNITS, SEISMIC PROFILE FACSIMILE RECORDER, SEISMIC PROFILER MAGNETIC TAPE RECORDERS, MARINE SEISMIC PROFILERS AND HIGH RESOLUTION AMPLIFIERS; [ TRANSITS, LEVELS, ALIDADES, CURRENT METERS, PRECISION STANDARD WEIGHTS AND MEASURES, INSTRUMENTS FOR TESTING AIR PERMEABILITY, POROSITY, STIFFNESS, ETC. OF PAPER AND TEXTILES; THEODOLITES, RETICLES, SCALES, ENCODERS AND METEOROLOGICAL INSTRUMENTS-NAMELY, WIND SPEED AND DIRECTION INSTRUMENTS AND WIND ALARM SYSTEMS; ] VACUUM GAUGES; PRESSURE, VELOCITY AND FLOW MEASURING INSTRUMENTS-NAMELY, FLOWMETERS, MASS FLOW TRANSDUCERS, TRACK PLOTTERS, MONITORSCOPES, POSITION INDICATORS AND RECORDERS, INTERVALOMETERS AND TRANSMITTERS; AUTOMATIC LIQUID SCINTILLATION + GAMMA COUNTERS, THERMOLUMINESCENT DOSIMETERS, RADIATION DOSIMETERS, THERMOELECTRIC GENERATORS, FUEL CELLS OF THE TYPE WHICH RECEIVE A CONTINUOUS SUPPLY OF REACTANTS FOR PRODUCING ELECTRICAL ENERGY AND THERMOELECTRIC GENERATORS; BENDING STRESS MONITORS; [ MILD, HARDFACING AND STAINLESS STEEL ELECTRODES; ] TRAVELING WAVE ELECTRON TUBES; [ AIRBORNE RADAR SYSTEMS, ANTENNA AND FEED SYSTEMS, RADAR AUGMENTERS AND BACKSCATTER RANGES; MONOPULSE RECEIVERS USED WITH GROUND-BASED TRACKING FOR SPACE EXPLORATION; ] MICROWAVE FILTERS, FREQUENCY MULTIPLEXERS, RF COAXIAL SWITCHES, RF WAVEGUIDE SWITCHES, FREQUENCY MULTIPLIERS; [ RECEIVERS, HEADPHONES, SPEAKER SYSTEMS, CARTRIDGE DECKS, MICROPHONES, BURGLAR ALARM SYSTEMS AND TRANSCEIVERS; ELECTRICAL CORD AND CABLE; ALUMINUM AND BRONZE ELECTRICAL CONNECTORS INCLUDING SPLIT BOLTS, CLAMPS, LUGS, TERMINALS AND COMPRESSION FITTINGS; ] AND HIGH TEMPERATURE WIRE, CABLE AND TUBING FOR ELECTRICAL SYSTEMS