LG XL7S Owner's Manual page 10

Attaching the ferrite core (optional)
A ferrite core may not be provided depending on national standards.
Attaching the ferrite core to the power cord cable
Attach the ferrite core to the cable to reduce radio noise.
a Pull Part [a] to open the ferrite core.
b Wind the power cord cable twice around the ferrite core.
c Close the ferrite core until you hear a click.
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