It’s where you blow into this little mouth piece. And the computer prints up a pattern and it tells us how much air you can blow out overall. And it compares it to how much air you can blow out in one second. And it gives us a number and we compare that to sort of national averages based on your age and height. It tells us not only if you have asthma but it tells us how well your asthma is controlled. So, it guides us when people come in and have problems, it tells us to what we need to do with the medicines.