Compact, lightweight and portable, Built-in flexible three –zone management system, Easy- to- read numbers, Measurement Range 60-800 L/min, EN ISO 23747 : 2009 compliance, CE approval, Suitable for use with disposable mouthpiece A Rossmax Peak Flow Meter is a small, portable device used to measure your ability to push air out of your lungs. PEFR is an important indicator of lung function and is beneficial to use when monitoring respiratory conditions such as asthma. Taking peak flow measures every day and keeping a record of the peak flow measures in a logbook can help you and your medical practitioner make important decisions about your treatment. You should use this meter and set its color zone indicators according to a treatment plan developed for you by your medical practitioner.