The essential elements of a Delcom eddy current meter’s sensor are inductors in ferrite cores. An inductor/ferrite assembly exists in both the top and the bottom parts of the sensor (except for the single-sided S3 sensor). In general, given a certain diameter of a pair of inductor/ferrite assemblies, the smaller the gap between these sensor halves, the better the performance, and the larger the gap the poorer the performance. Thus, it is best to work with the smallest possible gap suitable to the desired application, and it is important to carefully choose the Delcom meter with the proper gap.