I live in an extremely humid area and also sweat a lot, so fogging of lenses is a frequent problem. I decided to try these instead of my usual Rydons to see if the ventilation helped. They seemed ok, but at the midpoint stop, they started fogging up, and I was disappointed. But when I started riding again, it was like turning on the defroster in a car -- the lenses cleared right up -- amazing! My Rydons never cleared like this. Very impressed!