Material Spieler reports about the Uvex F1 Magic Goggles.
"Uvex F1 Magic Goggles offer an all-in-one solution with the help of pioneering technology. The Goggles feature a lens which was originally developed by AlphaMicron Inc. for the US Air Force. Its VALiD lens (Variable Attenuation Liquid Crystal Device) switches the tint of the lens from a light high contrast to dark with a click.
How does it work? A composite of dyes and liquid crystals is sandwiched between a conductor-coated double lens. A low dose of voltage causes an electro-optic response of the liquid crystals to alter the light transmission characteristics of the lens. "
More details on Material Spieler.