Check the listing for details. RFI Ferrite Choke Clamp-on core / one (1) large. Condition: New. Listed at 8.99 USD. "The common-mode filter or choke may be one of the best-kept secrets" American Radio Relay League Antenna Handbook RFI Ferrite Clamp-on largeTame your RF Interference (RFI) with Clamp-On! Use these Clamp-On ferrites as RFI suppressors on your radio and shack equipment. If you experiencing any RFI problems in your home just put these on your power supply cables, Computer cables, speakers, modems etc. Just wind 4-8 turns (passes) thru each for best results.One (1) large Clamp-on suitable for power supply cables or any larger diameter cables like computer network cables, speaker cables, antenna cables etc.Dimmmmm tolnominal inchinch misc.A38.6_1.52_B18.35_0.722_C47.5_1.87_D19.15_0.755_Cable InformationMax DiameterMax DimensionSolid EquivalentFlat Cable Cores18 0.709__-