This is by far the best antifog product I have used. It lasts through multiple swim days and does not sting eyes. The coating needs to be well wet before wearing, otherwise it will not prevent fogging. I like to keep a small puddle of water in the eyecups to keep the coating in its best wetting condition. Reapplying is easy, just brush a new layer over the old one and let it dry. When there are three or four layers built up, I do a deep cleaning. This is also simple, just leave a few drops of water on the lenses and wipe the coating off with the microfiber cloth that comes with the brush pen.