EMI filters suppress noise in electric currents that are conducted through wiring such as power cables and conductor paths. A common mode choke is an EMI filter that blocks high frequency noise common to two or more data or power lines while allowing the desired DC or low-frequency signal to pass. Filter kits allow for experimentation with varying sizes and types of filters including chokes, ferrite disks, plates, beads and chips, transformers, cores, resonators, and saw filters.