The 71-3A Decade Capacitor is a three-terminal capacitor with selectable values of capacitance from 1 pF to 1221 pF in 1 pF increments. The unit can be used as a secondary standard for the calibration of capacitance bridges or capacitance meters. It may also be used as a reference capacitor for differential capacitance measurements. Frequency range is 100kHz to 1MHz.