Dont bother getting a cheap mask like this.
This thing is supposed to "protect" your full face and eyes, and its on 42 dollars....hmmm.
PLus the fact that a few friends of mine bought similar masks and when we fired at them with stock guns the lense pieces poped out easily and the mask started chipping apart. Not something you would want to put your trust in.
If you absolutely must have a mask like this (great for cqb!) check out my review of a quality full face mask that you can get from the Philippines custom made for you. I run it all the time and ive been shot in the eyes quite a few times...and still not a single scratch or scare!
http://www.airsoftcanada.com/showthread.php?t=139518