Eddy current meters usually have a top and a bottom inductor. Material reads as a higher sheet resistance in the exact middle elevation between the top and the bottom halves of the sensor. If the material is moved towards either the top or the bottom half of the sensor, the material will read as a lower sheet resistance. Thus, it is imperative that material being measured is either introduced to the sensor at the magnetic center or that the sensor is calibrated to expect the material at another elevation and that the material is consistently inputted at that exact elevation. Delcom makes stages for benchtop sensors which aid greatly in achieving elevation consistency.