Bruce L. Bergman writes:

They don't have to be "government approved".

The EPA via the Clean Air Act regulates what fittings can be used with what
refrigerants. Not the marketplace, not engineering standards, not the
convenience or expedience of you or me or the OP. I don't agree with the
despotism of the government, I'm just warning you. The law makes us all
criminals, even for things like cutting metal. The tender mercies of the
bureaucrats decide who is punished and who is given lenience.