Ixnay the Og-fay The Nerdwax FogBlock is a reusable coated microfiber cloth that keeps your lenses fog free. Simply breathe on your lenses to fog them, then wipe evenly with cloth... boom! You are now UnFogettable. Buy 3 and Save - 1 for work, 1 for home, and 1 for a friend! Safe to use on all types of lenses and coatings including AR coatings*. Stays effective for 1 year or 300 applications when kept in pouch. Does not contain PFOA/PFOS, CMIT or MIT. * we've heard from some users that it does not work as well on Crizal lenses