GDDO-20C AC / DC Electric Meter Calibration Device yog siv los txheeb xyuas qhov yuam kev ntawm ntau lub zog zaus hluav taws xob hauv cov tshuab hluav taws xob, suav nrog voltmeter, ammeter, wattmeter, ohmmeter, ib theem & peb theem AC lub zog ntsuas (yeem) thiab qhov yuam kev yooj yim ntawm DC volt-meter thiab ammeter.