Been carrying around two pair of safety glasses? Clear lens for inside work, and grey lens for outdoors. Tired of setting one pair down and having to retrieve them from your last task?
The 3M SmartLens is "UV reactive", also called "photochromic", so it responds to the amount of Ultraviolet (UV) light it receives. The lens lightens or darkens as needed...going from clear to gray. Now you can enjoy the convenience of using a single pair of safety glasses for both indoor and outdoor protection. Awesome!
The photochromic lens for the 3M SmartLens has a 22% VLT (visible light transmission) in its darkened state. This can be considered a medium gray, and not as dark as some might require in bright sunlight. As a comparison, typical dark gray lenses allow only 10-16% light transmission.
Just a friendly reminder when driving, our windshields are made from polycarbonate which is 99.9% UV protective by nature. Photochromic lenses won't darken when worn inside a vehicle, because the vehicles windows are blocking the necessary UV light, which causes the lens to darken.