Review on 20pcs Clip-on Ferrite Ring Core Black RFI EMI Noise Suppressor Cable Clip - Enhance Signal Quality and Reduce Interference by Leon Yulharmanto

Unlike most other 20-piece ferrite choke sets on Revain under $10, this set lacks the smallest 3mm size, instead each containing an extra Piece from other, more useful sizes. - so 5x each of the 4 sizes, not 4x each of the 5 sizes. I found the 7mm size to fit a standard electrical lamp cord, 2 conductors of 16 AWG insulated lightning cord. Size 9 mm fits 2 conductors 12 AWG, in my case 12 VDC output from switching power supply. (See photo.) It would be nice to know what type of ferrite material was used to see the electrical characteristics, but 45 cents for a choke is an unrealistic expectation. For the price they appear to be well made and were shipped securely, all arrived undamaged.