I have one, I think it's called a Peak Flow reading. I use one occasionally to see where I am. I'm 5'4, female and my recent readings are around 280-300. By best EVER reading was over 500! Everyone was blown away, myself included. That only lasted for a little while though. I've been told that it's not only dependant on hieght but the size of your lungs, weight etc. Just for fun I've had my husband do it to see what a health guy's might be. He is 6'2, 240lb, and his reading went to the top of the darn thing.....800+! Geezlaweez.