It works! I have a chronic cough after lung infection, caused by chest congestion. Nothing helps it, and during covid, people look at you like you’re a leper if you cough. I’m using it 10-15 minutes daily. After about 3 days, there was dramatic improvement. It really brings up the phlegm on *your* terms, when you want to bring it up. The device is a nice size, nicely built, easy to clean. It survived a fall onto the floor from 4 feet.