Review on Festnight Multifunctional Detector Analyzer Protable by Paul Wilson

I used it in my room to find out when to open the windows. Because of the cold weather and the strong wind, I have to close the windows most of the time. I used it to monitor the area and when it's dirty I open the window. After a while it will show up well. While I don't know if the numbers are correct (I have no way of knowing), I have a feeling this is a good aerial monitor as it can actually tell the difference after I open the window.