Production and sales of electronic instruments and meters: DO30, D030, Multimeter Calibrator, Multifunctional Calibrator, Clamp Meter Calibrator, Multimeter Verification Device, AC/DC Standard Source, Optical Coincidence Level, Bar Level, Frame Level, Concentricity Measuring Instrument, V-block, V-iron, Megohmmeter Calibrator, Megohmmeter Verification Device, Insulation Resistance Meter Verification Device, Ground Resistance Meter Calibrator, Ground Resistance Meter Verification Device, Multimeter Calibrator, Multifunctional Calibrator, Multifunctional Calibration Source.