The F-40 has a typical transfer impedance of 1W(± 2 dB) over the frequency range of 10 kHz to 20 MHz. The probe will not saturate when clamped around conductors carrying 350 amperes of DC to 400 Hz, 100 amperes of CW and 200 amperes of pulse currents. It has a usable frequency range of 10 Hz to 20 MHz.