Meters, measuring apparatus, instruments and appliances, namely, pH-meters, conductivity meters, dissolved oxygen meters, redox meters, photometers, spectrophotometers, and multi-parameter meters, namely, combined pH, ion selective electrode (ISE), conductivity and dissolved oxygen (D.O.), oxidation reduction potential (ORP), and T meters; titrators, piston burettes, sample changers, namely, sample containers for laboratory testing; stirrers for laboratory use, titration vessels, titration ti...