To be honest, I used this for only 3 games. Once twice indoor, once outdoor. Indoor, it helped A LITTLE, in that turning it on helped slow the rate of fogging, but not stop. Outdoor in 4oC conditions, it proved absolutly useless. No fog protection whatsoever. The last time i played indoors, I took a goggle shot, and the fan broke.
It was half decent indoor, but it also broke very, very easily. So, useless in my opinion.