Abstract: A signal filter is disclosed herein for the filtering of electromagnetic interference carried by an electrical conductor having a housing enclosing a core of soft ferrite composition with a weak magnetic field impressed upon it adapted to be placed about the electrical conductor having a directional signal flow within the electromagnetic generation pattern of the conductor to absorb signal interference emission accompanying a transmitted signal. The housing has an indicator identifying magnetic flux directional polarity of the core. The housing may include a retaining strap or securement prongs that engage with the cable to maintain the filter in place.