This device helps you relearn how to take slow, deep breaths. The mouthpiece is connected to the device by a flexible tube. When you inhale, the suction will raise a ball or other marker within a clear cylinder; when you exhale the ball will fall down again. The goal is, with each inhale, to steadily raise and keep the ball hovering until you breathe out. Do this several times, and repeat every hour, or as your doctor recommends.