5pcs 42X24X16mm Toroid Core,Ferrite Rings Toroid Core Iron (Black)

You have to put both line and neutral or lin and line through the choke.

good Quality

These toroids arrived promptly and were undamaged and as described. The size is good for thin coaxial cable and unterminated power lines. These did the trick to eliminate common mode current back into my transciever from a longwire on a 9:1 balun. I also have an air wound choke on the line which lowers, but does not stop common mode current, and which only reduces noice on part of the spectrum. The addition of this toroid to the feedline stopped the CMC and quieted down noise accross the spectrum. If you are looking for a toroid to use on 110ac wires with standard or grounded plugs you will need a larger size, these would be perfect for DC lines from your power supply. I am unsure of the mix, but will attemp to build a few baluns/ununs in the future and see how they perform. This is a great price and they are good toroids.

I misunderstood what they are. They break easily. They are useful.

Calculate size you need before buying. Fun to play with. I glue 3 together to increase inductance before winding voils.