As you mach down singletrack or run along shady trails, the Oakley Flak Jacket Transitions Sunglasses adapt to changing light conditions to give you unparalleled visual clarity. Activated by Transitions technology means the Flak Jacket Sunglasses lenses lighten to show hazards on shaded paths, and darken to shield your eyes in the sunshine. This technology works with balanced light filtering and Oakleys High Definition Optics to bring you outstanding color contrast, clarity, and depth perceptioneven in low light conditions. O Matter frames make the Flak Jacket Sunglasses feel incredibly lightweight, increase durability, and create balanced pressure points for a comfortable fit. When you work up a sweat, Unobtainium nose pads and stem sleeves increase their grip so these Oakleys wont slip off your face.