Review on Topnisus [Pack of 10] Clip-on Ferrite Core Ring Bead Cable Clip - Anti-Interference Filter for RFI EMI Noise Suppression, High-Frequency Optimization (5mm Inner Diameter) by William Auditore

These ferrite cores worked exactly, I heard the difference immediately. I have a set of speakers and a subwoofer that spoke so badly through my new phone that it was impossible to hear them. I attached 2 of these clip-on strands to the back end of the cord, right next to the exit - there was a left cord and a right cord, so I attached a clip to each strand. Feedback is completely gone. Highly recommended.