Purchased this mask because my previous mask kept fogging up on me and i was sick and tired of it. Bought this mask new for $15 with two thermal lenses. The mask has never fogged up on me and gives a great (270 degree) field of vision. I will never go back to the other masks i was using.
Buy it if you can get it cheap 15-20. even for a backup mask it is great. The dyes and other high end masks are better, but also three times the price. For overall value this mask is best.