Don't waste your money. Use a glass of water and a straw. Just blow in the straw as long as you can (Making bubbles). It is amazing how your time blowing on the straw will increase. It helps loosen mucus. I swear by doing it.
The respiratory tech gave me one when I was in the hospital with pneumonia. It works. Hope everyone is breathing easy today. It is humid and hot here.
It's hand held, you breathe in it and when you do it flutters, it's to loosen up the mucus in your lungs so you can bring it up.
I use a flutter pipe . Handy in the pocket. Certainly works.. ☺ 🍀