The bugs have been so terrible this year that I've left this on my QH almost 24/7. With that said, it's looking pretty worn (what fly mask doesn't get worn out with that kind of use?). It will definitely need replacement at the end of the season, but even before it started looking worn, small gnats can slip through the ear mesh. Not a huge deal, but enough to make my QH rub his head on trees and further damage the fly mask. Even with it being on nearly all of the time, it seems to be comfortable for my gelding and he willing accepts it when I put it back on.