Personal Best encourages compliance with its comfortable oval mouthpiece and easy-to-use built-in handle. This unit's lightweight and self-contained design makes it easy to test your peak flow anywhere at any time. The Personal Best Peak Flow meter can be easily sterilized on the top rack of a dishwasher. And it's easy to understand with its high-legibility scale and NAEPP-endorsed three-zone management system. A peak flow meter helps you determine when an asthma attack has a higher probability of occurring because it lets you measure your lung function and compare your daily values to determine the effectiveness of your asthma management.