Yes @KITROBASKIN you are correct. I do have water lines that run through my attic. One of them burst 2 years ago. I had my plumber install an air coupling inline so that I could blow out the two lines that go to my outdoor faucets.The Poppy situation involves pipes going up to, then across the attic, then down (I think). Using air compressed solves the matter of trapped water in his pipes (hoses?)
After I blow out the lines, I then pump RV antifreeze into them, just incase there is a belly in the line that the air got through, and then water still in the line settled back.
Only after I bought those other adapters, did I come to think that I probably could have connected my air hose to the side of the house, and blow the lines out to the faucet in the back of the house.
I did use those adapters on my garden hoses, although I disconnected them and did the walk back hand over hand with them over my head. I did it while blowing air through them. Not really necessary, but I had to put them to use. giggle.