What are the black plastic cylinders 4" from each end of my TV's mains power cable?

Question

I've got a mains power cable with my new TV. It's got a normal plug at one end and a IEC end (like a power cable for an old kettle or a PC).

About 4" from each end is a plastic cylinder wrapped around the cable. They are about 3/4" in diameter and approx 1 1/2" in length.

What are they?

Answer 1

inside the plastic cylinders there are ferrite inductors and its use is for interference suppression. nothing to worry about

Answer 2

They are ferrite clamps, fitted to reduce RF (radio frequency) interference from the cable.

Any cable with a current running through it will try to act like a radio aerial.  This causes interference on your TV, hi-fi, A/V system, or whatever.

Better quality mains leads have ferrite clamps to help reduce the interference from RF signals.