Yes, it is a bit overpriced for what is a bit of plastic and a big ball bearing.
Yes, it works.
Your goal? Make the ball bearing vibrate with your breath and see the mucus collect in the top of the device and you’ll cough for a while afterwards. Sounds stupid, but oh my days it really does work. After the very first use my asthma wheeze and cough just disappeared. My lung capacity is so much better, I can take deep breaths for the first time in years. I haven’t needed my ventolin for days now. If you can’t get the ball bearing to move, I suggest youtube videos to help you and most importantly, don’t give up. Don’t give up because this product (while expensive) actually does work. I’ve gone from blowing 260 on my peak flow, to a rather incredible 500. It’s nearly doubled my lung capacity. I’ve got more energy than I have ever had in my entire life.
No question about it. The best money I ve ever spent as it has completely CHANGED MY LIFE!!!