This is a great mask. I primarily purchased this to use when power washing tractor trailers because I use some very corrosive soaps and aluminum brighteners (containing hydrofluoric acid) to clean the trucks. I have one for both myself and my helper. We both have large heads and facial hair but I still find that the mask creates a good enough of a seal that I do not smell any of the vapor, or feel effected,  from the chemicals nor do I feel like anything is  getting into the mask. I have also found myself using this whenever Im doing woodworking projects or even cutting my hunting arrows. Just whenever I feel like my breathing and lungs are at risk this is my go to. It is very lite and non-intrusive. My favorite part is that it doesnt fog up my safety glasses or sunglasses when Im using it. Cant tell you how frustrating it is to be working, sweating and not being able to see jack in front of you. With these thats not an issue with it exhalation valve in the front. Not like wearing a paper mask where everything escapes through the top and into your glasses. Also its easy to just pull the top strap off you head and let the mask just hang when you are not using it. Im constantly putting it on and taking it off so its nice to have it hanging their comfortably and not being a nightmare to put back on and take off time and time again. It is 100% worth the money.