The GR 1822 is a very flexible and capable DC voltage calibrator with many features not found on other calibrators: ranges of 1 mV to 1000 volts, manual or auto steps in 10% increments to full range, repeat digits, selectable output resistances of 0 ohms, 1000 ohms, 10k ohms or 100k ohms, etc. This is an excellent voltmeter calibrator from the experts at General Radio.