Interchangeable lenses are generally pretty convenient before a ride, but they can be tricky to change while you're in the saddle, not to mention tough to safely carry in a saddle pack or jersey pocket. If your rides regularly include riding along sunny hills, dropping into shady canyon descents, and popping out in into bright neighborhood streets, you'd probably appreciate the futuristic photochromic tint changing technology in Uvex's Variotronic FF Sunglasses. All new for this year, the Variotronic FF uses a layered polycarbonate and liquid crystal laminate construction that responds to light levels detected by a photocell light sensor. This technology permits 64% of light to pass through the lenses when your climb takes you into a mountainside tunnel and darkens upon exiting to allow just 16% of light to reach your eyes, and does so in just a fraction of a second. The power for this technology, called E Tint, comes from a small, rechargeable accumulator the size of a small magnet. It locks into the frame of the glasses and is capable of holding a charge for about 50 hours. When you're out on a ride, you have the opportunity to allowing the accumulator to auto adjust to light conditions, or you can toggle between on, off, and auto modes using a single easy to feel button. Proposition 65 Warning for California Consumers: This product contains chemicals known to the State of California to cause cancer andor birth defects or other reproductive harm.