You can set the device up to offer resistance against either inhalation or exhalation. It is good for people who have COPD, or looking to increase their lung abilities for exercise.
Does inhaling against resistance have any health risks (can it damage anything in the lungs)? I assume exhaling against resistance isn’t a problem (if so blowing up a balloon would cause problems), what about inhaling?
After my operation while I was still in the hospital, they gave me a device I was to inhale through. It was certainly harder than inhaling. There was some resistance as it had several small blue balls and if you were doing it right you could make one to four of them float in their chambers. I believe this device was to help prevent post-operative pneumonia. So inhaling against some resistance can’t be too bad for you.