Since the Uvex Variotronic Shield Sunglasses adjust tinting within a tenth of a second to match changing light conditions, they're ideal for virtually any training ride or race but are especially welcome during the shoulder seasons when cloud dover and conditions can be unpredictable. The Variotronic lenses go from clear 64% light transmission to shaded 16% light transmission at the press of a button located at the left temple alternately, they can be left to adjust automatically like any pair of photochromic sunglasses. This rapid transition is made possible by E tint technology, which combines a light sensor with a specifically developed liquid crystal lamination. E tint powers this electrochromatic technology with a tiny, rechargeable accumulator that gives up to fifty hours of power. The Variotronic Shield Sunglasses also exhibit some less technical but just as important features, including a Supravision coating for anti fog convenience and scratch resistant protection. The lenses also block 100% of UV rays and offer additional impact resistance, and the frames are finished with soft, adjustable nose and temple pads to provide a specific fit.