Rockwork Photochromatic Cycling Sunglasses White and BlackThe Rockwork is the latest version on the very popular and long lived Hijack. Though it has some familiar looking lines, the entire frame and lens have been redesigned for elevated style and performance. WHEN THE SUNLIGHT CHANGES, THE TINT CHANGES. The science behind it is complicated but the result is as simple as that. Each Photochromic lens contains millions of organic molecules that react to UV light. When exposed, the molecules change shape,