Simply place the mouthpiece in mouth and adjust the single adjustment knob to provide the preferred amount of air resistance. Lets you gradually strenghten lungs. Many people experience quick improvement. Used by rehab patients, competitive athletes, COPD and many more to make lungs more effective and efficient in pulling in oxygen and pushing out CO2. A new Harvard study shows strengthening breathing muscles helped many adults naturally lower their blood pressure. Easier breathing and more nourishing oxygen can lead to improved sleep. It can open airways into your lungs that have been partially blocked over the years due to natural aging, pollution, poor physical condition, or smoking.