When you have asthma you have to use a peak flow meter measures the flow of air as it's expelled from the lungs. To do this, you or your child will blow into the peak flow meter (as if blowing up a balloon). A marker will slide up a scale on the meter as you or your child blows out to indicate how much air was exhaled. The peak flow is the number where the marker stops on the scale.
I recently got to review Asthma MD Peak Flow Meter and as a asthmatic which comes and goes I need to keep track of the lung progress I have and blow on this and then report to a doctor from time to time as the treatment you currently have may not be working. This peak flow meter was created by a doctor which has a 3 zone management system where you can keep a paper log or download the app.
My Opinion: My Lungs are not the best I could only get it to 200 which is normal for me and the place you blow into needs to be smaller for me as I have a hard time making a good seal.
To learn more visit http://www.asthmamd.org/peakflowmeter/
Where to buy? CVS, Walgreens and Amazon
Disclaimer: I was in no way compensated for this review and this is solely my own opinion which may differ from yours.