Optical, electrotechnical and electronic measuring apparatus, in particular for measuring fine dust, nanoparticles, gases, vapors, and aerosols; measuring apparatus and test benches for measuring the efficiency and filtration capacity of filter systems; scientific apparatus for determining particle size or particle size distribution, the number and size of particles; filter testing apparatus, namely, laboratory optical devices, non-medial respirator masks, aerosol spectrometers, counters and sizers using optical laser scattering, and portable aerosol spectrometers; scientific apparatus for determining particle load in air, gases, vapors and aerosols; aerosol and dust generators for calibration and to simulate medical or toxicological use; identity cards and identity passes, magnetic; apparatus for recording, collating and evaluating data; electronic computers for controlling and regulating their peripheral devices, in particular screens, printers and test desks and remote control apparatus; software for controlling and regulating electronic computers used for controlling and regulating their peripheral devices, in particular screens, printers and test desks and remote control apparatus; OF "GROUP"; Calibration and function testing of measuring apparatus; engineering, namely, scientific and industrial research in the field of aerosol technology, construction drafting; providing technical advice in the field of scientific and industrial research; computer programming for logging, processing, evaluating and storing measurements, and for controlling and regulating measuring apparatus
