Pinnacle is a peak flow meter which measures the patient's maximum speed of expiration, or peak expiratory flow rate (PEFR or PEF). Peak flow readings are higher when patients are well, and lower when the airways are constricted. From changes in recorded values, patients and doctors may determine lung functionality, severity of asthma symptoms, and treatment options. People with asthma may benefit from regular peak flow monitoring. When peak flow is being monitored regularly, the results may be recorded on a monthly peak flow chart (supplied with Pinnacle). The Pinnacle peak flow meter family is now used worldwide. It was designed specifically to meet and exceed demanding new International Standards.