The Quest Peak Flow Meter measures how well your lungs are able to expel air. You can learn to use this simple device to monitor your asthma and head off attacks before they occur. The Quest Peak Flow Meter is the most accurate Peak Flow Meter in its class, with an accuracy rate of ± 4%, three times better than the industry standard. The Quest Peak Flow Meter is a full range meter that measures one’s exhalation capacity, known as peak expiratory flow (PEF). Measuring your peak expiratory flow helps to manage asthma symptoms and head off attacks before they occur. The Quest Peak Flow Meter is the most accurate Peak Flow Meter in its class, with an accuracy rate of ± 4%, three times better than the industry standard. Ergonomic mouthpiece and curved contours makes it easy to use and comfortable for patients of all ages. The Quest Peak Flow Meter has two adjustable zone indicators that correspond with the red, yellow, and green zones of a user’s asthma action plan. . Its measuring range is from 60 to 810 liters per minute. These zone indicators correspond with the red, yellow, and green zones of a user’s asthma action plan. The scale has major scale interval markings at 50 l/m, minor scale interval markings at 10 l/m. FDA 510(K) cleared.