Apertometers; Binoculars; Microphones; Microscopes; Periscopes; Photometers; Refractometers; Spectroscopes; Stereoscopes; Astronomical spectrographs; Inspection mirrors; Lenses for astrophotography; Magnifying glasses; Micrometer screws; Oculars; Optical condensers; Optical lamps; Optical lenses; Optical glasses; Optical reflectors; Prisms for optics purposes; Sighting telescopes for firearms; Spectrograph apparatus; Telescopes; Cover glass for microscope slides; Electron microscopes; Microsc...