[ Electric sensors; Meteorological instruments; Optical apparatus and instruments, namely, optical ports for underwater photography, dome ports for underwater photography, wet diopters, adapter lenses for underwater photography; Passive infrared detectors; Photographic exposure meters; Photometers; Scientific apparatus, namely, spectrometers and parts and fittings therefor; Spectrograph apparatus; Stroboscopes; Surveying machines and instruments; ] Telecommunication exchangers; Voltage stabil...