RF Blocker Ferrite Choke Noise Supressor
Ferrite beads prevent interference in two directions: from a device or to a device.
A conductive cable acts as an antenna – if the device produces radio frequency energy, this can be transmitted through the cable, which acts as an unintentional radiator. In this case the bead is required for regulatory compliance, to reduce Electro Magnetic Interference
This is particularly common on data cables for instance if you were to use your USB Car Charger you may hear interference in your car radio. These RF noise suppressers will eliminate that noise.