Molecule Labs Anti-Fog spray is formulated for use inside your helmet visor, goggles, windshield -- even your glasses. Simply spray on two coats and wipe clear to prevent moisture from condensing into a fog. 4 ounce pump spray bottle is enough for many faceshields, or two to four windshields.
Note: Because of the wide variety of plastic formulations, always test any spray like this on a small area to determine compatibility first. Not for use on Stilo shields or "Fog-Free" shields or shield overlays.