Review on Stardrift 10-Pack 13Mm Diameter Snap On Ferrite Core Bead Choke Ring Cord RFI EMI Noise Suppressor Filter For HDMI DVI VGA Cable Black (13MM) by Steve Quinn

Update: I managed to figure out how to install them: use pliers. At first I only tried this with my hands and could not close them on the wire. The pliers are doing their job. Once opened they close with two small latches (with a simple pocket knife) and are VERY difficult to close again. They fit snugly on the center cable wire, but if you "squeeze" them with pliers, they work great. Warning: It's (fairly) easy to break the magnets, but be careful.