F.W. Bell Sypris tesla meter 0 - 20 kHz with FW Bell STD61-0402-05 Transverse Probe and 5 ft. Cable. Measure the residual magnetic field at the site of your experiment. This magnetic field residual may be due to magnetisation of steel reinforcement or steel structure of the building. Zero the meter and probe, with a zero field gauss chamber, before taking the reading. This meter can be powered by the line voltage or taken in the field and run off the battery. The battery is fully charged.