9 Mathematical instruments, namely, slide rules, calculators; time and date stamping machines; time recording devices, namely, time clocks; punched card office machines; voting machines; postage stamp checking apparatus, namely, an apparatus used to confirm attachment of postage stamps; fire extinguishers; fire hose nozzles; sprinkler systems for fire protection; fire alarms; gas alarms; anti-theft warning apparatus, namely, home alarms and home burglar alarms; protective helmets; laboratory apparatus and instruments, namely, constant temperature incubators for laboratory use, constant humidity incubators for laboratory use; optical machines and apparatus, namely, microscopes, magnifying glasses; measuring machines and instruments, namely, temperature indicators, gasometers, balances, tape measures, pressure gauges, tachometers, photometers, hygrometers, illuminometers, speed indicators, viscosimeters, flowmeters, surface roughness testing machines and instruments, metal hardness testing machines, laser level measuring apparatus; testing machines and instruments for testing asphalt, textiles, plastics; power distribution or control machines and apparatus, namely, relays, electric, circuit breakers, current rectifiers, lightning arresters, electric transformers; rotary converters; batteries and electrical cells; electric or magnetic meters and testers, namely, circuit testers, magnetometers, resistance measuring instruments; electric wires and cables; electric buzzers; telecommunication machines and apparatus, namely, intercoms, telephone sets, sound recording apparatus; computers and their peripherals; downloadable and recorded computer programs used for developing, designing, manufacturing, processing, ordering or delivering products or their parts; electronic machines and apparatus, namely, computers, hard disk drives, electronic circuits, mouse pads for computers; magnetic cores; resistance wires; electrodes, other than welding electrodes or medical electrodes; gloves for protection against accidents; dust masks; gas masks; welding masks; fireproof garments; spectacles, namely, eyeglasses and goggles; downloadable electronic publications, namely, manuals in the field of manufacturing