The incentive spirometer, or Inspiron [Inspirx®], is a device used to give respiratory patients a visual demonstration of how much air they can inhale. While this was designed for inhalation, if it is turned upside down, it can also be used for exhalation. There is a gauge to adjust resistance and the Inspiron can also be used in conjunction with mouthpiece practice.
Great tool to kickstart your air usage. I attach my mouthpiece, flip the Inspiron upside down, and buzz through my passages. Highly recommend!