KNOXZY Peak Flow Meter is a portable, handheld device that measures your ability to exhale air from your lungs and provides an accurate picture of airway ventilation. KNOXZY Peak Flow Meter is perfect for athletes and exercisers, oxygen users and asthmatics. KNOXZY Peak Flow Meter is a Lung capacity tester helps to detect asthma attacks early accurate measurement flow. Dual flow range measures accurately for both adults and children. Instant readings track changes in airflow to detect asthmatic problems, the peak flow meter. KNOXZY Peak Flow Meter is Washable and can be used with disposable mouthpiece.