The meter are suitable for measuring when frequency is within the range from 5Hz to 1MHz, voltage is from 30μV to 100V. They feature low small frequency response error, high input impedance, high-resolution, high-accuracy, good--linear. No zero-adjusting need when switching the range of measurement, high-sensitivity. They can be used as a broad-band preamplifier and widely used in factory, laboratory, scientific research unit, military and university.