Designed to block out exceeding light and to enable the spotting of road signs, pointing out red and green colors. POLARIZED to block out blinding glare and have optimum visual acuity for safe driving. One of the characteristic features of Drivewear is that they are the only photochromatic lenses that darken behind the the windshield of the car. If exposed to sunlight, the Drivewear lenses turn into a copper color which many consider the best color for a driving . This should not surprise, as Drivewear color has been thought to remove exceeding light and to allow the driver to provide good traffic signals recognition.