Hi Beijingers, I'm selling my great Laser Egg air quality monitor in absolutely perfect condition. I bought it for 500RMB a few months ago and I'm selling no for only 300RMB. (no bargaining please) This is a must-have in Beijing, since it tells you instantly and accurately what's in the air quality you're breathing, allow you to take measures to protect yourself and your family from the serious air pollution problems. The laser egg provides air quality readings in real-time, displaying the values on the LED screen as PM2.5 concentration, AQI and particle count.