Bell - MX-9 Adventure Transitions Face Shield

Photochromic technology allows visors to automatically and seamlessly change from clear to dark in sunlight. The process works when photochromic dyes embedded into the lens orshield react to UV light, changing levels of darkness with the sun. When UV light is removed, a chemical reaction driven by ambient heat reconverts the activated photochromic molecules to their original, clear form and the lens fades.

The amount darkening is a function of the competition between the activating and fading chemical reactions, the equilibrium condition established between them, and the specific photochromic molecules and the lens substrate. The more activated photochromic molecules that are present, the darker a lens becomes. The degree of darkness depends on the level of available UV radiation driving the activation reaction and the temperature of the lens, which drives the fade reaction.