Hoʻohana ʻia ʻo GDDO-20C AC/DC Electric Meter Calibration Device no ka ʻike ʻana i ka hewa kumu o nā ʻano mea kani uila uila i nā ʻōnaehana mana, me ka voltmeter, ammeter, wattmeter, ohmmeter, hoʻokahi manawa & ʻekolu manawa AC ikehu mika (koho) a me ka hewa kumu o DC volt-mika a me ka ammeter.