The 887AB Differential Voltmeter is very accurate. The principal advantage is its extremely high input impedance for dc "at null," a setting where input voltage is most accurately measured. When measuring voltage from relatively high impedance sources, the input impedance of any voltmeter acts as a load and has a very significant effect on the accuracy of the measurement. This instrument reduces the measurement error in such cases. Range from 0-1100 VAC and DC. Null ranges of 100 µV through 100 V AC and DC, in 7 ranges. Rechargeable battery. DC accuracy of ±0.0025%, AC accuracy of ±0.05%.