Analytical and measuring apparatus and instruments, namely, water quality testing instrumentation for monitoring and detecting physical and chemical characteristics of water, ph meters and testers, apparatus for water quality or solution analysis with measurement and testing of oxidation reduction potential (ORP), ion meters and testers, conductivity meters and testers, salt meters and testers, total dissolved solids (TDS) meters and testers, electrodes used as parts of water quality or solution analysis apparatus, sensors used for water quality or solution analysis apparatus, assemblies used for water quality or solution analysis apparatus, accessories used for water quality or solution analysis apparatus, combined meters and testers for water quality or solution analysis, compact meters and testers for water quality or solution analysis.