These instruments are millivokmeters and voltmeters with mean value indicating devices that offer offective value calibration, and are used for measuring sine wave alternating current voltages of ΙΟΟμν — 300V [150V — 500V] in the 5Hz — 1MHz frequency range. These instruments are highly sensitive and precise. New circuitry insures wide range readings with excellent linearity characteristics. The use of output terminals enables application of these units as wide-band high gain amplifiers or pre-amplifiers on other electronic apparatus. 2. Features 1. Wide band-width of 5Hz — 1MHz. 2. High accuracy; ±2%. 3. Highly precise, reliable and stable voltmeters of new circuit design. 4. Wide-use voltmeters with two decibel scales (OdB - IV. OdB ~ 0.775V) in addition to the effective voltage scales. 5. The output is calibrated at lVrms full scale, so that these instruments can be used as low~noise high-gain pre-amplifiers on wave form monitors.