Ever wonder what's inside those "sealed" baluns? Certainly seems there are many manufacturers who would prefer you not know. Over the years we have collected pictures of many of these units and here are a few examples for comparison. First here is our model 4115 which is a dual core, 5kW 4:1 current balun.
Here are some of the same offerings from other companies.
Next we have our model 4113 which is a single core, 4:1 current balun, 3kW unit.
And again those that would call theirs the same.
Lastly the venerable 1:1 current/isolation/choke/feedline balun Here are models 1115 and 1116d.
With competitive offerings for your comparison.
In the immortal words of John Ruskin, "There is hardly anything in the world that some man cannot make a little worse and sell a little cheaper, and the people who consider price only are this man's lawful prey".