Rectangular Snap Fixing Cable Ferrites. From Richco, these snap-fixing ferrite cores are designed to attach to cables in order to reduce electromagnetic interference from being induced or radiated. The ferrite is housed in a hinged nylon 66 carrier, which is simply snapped around cable and is supplied with a cable tie which can be used to prevent the ferrite sliding along cable when attached to the integral retaining lug. Applications for Snap-Fixing Cable Ferrites:. Rectangular ferrites are suitable for data cables e.g. telephone or signal lines. Circular ferrites are suitable for mains cables e.g. on photocopying machines, printers and other office equipment.