Electronic components and assemblies for selected frequency-range wireless communication, namely, transmit and receive filters, low-loss resonators and ceramic filters, high-selectivity filters, station and mobile duplexers, power switches and couplers, and tunable cellular test systems, namely, tunable filters

water filtration systems namely water filtration cartridges, pressure gauges, activating valve and water conditioning cartridges and replacement parts therefore, for use in the graphic arts, photographic, food service, water treatment, printing and medical imaging industries