10 Pcs UF90B Clip-on Ferrite Ring Core Black for 9mm Diameter Cable
These fit AC Cords quite well, and they do have an effect.  I suggest buying a package of each size so you can match them to the cable and get a tight fit.  You can put more than one on a cable if required.  They will keep transmitter RF out of your computer and RF it generates out of your receiver - IF THE PATH WAS THROUGH THE CABLES.<br /><br />Some video cables do not have these, and adding them can dramatically reduce the RF generated by the video when the screen is showing a mostly white large object. 