Sparrowhyperion:
I was thinking the same thing. You kind of get what you pay for with brushes. The Harbor Freight brushes I believe are made by the same company who made my old Master G23. It had problems with bad fitting seals from day 1, Which is why I went to the Anthem 155. The Master had small leaks around the place where the tube goes into the jar, and as I found out a few weeks later, it had a small one just at the point where the tip assembly screws onto the body of the brush.
Yes, they are most likely all products of Fengda in China & reviews of these brushes is a bit on the variable side. They are fine when they work, but seem almost as likely not to work, with issues surrounding seal & thread quality.
As they say in another trade, mileage may vary (considerably in this case)!