SwitchLock technology makes changing Split Jacket lenses easy. Flick the SwitchLock, swap to the spare lens that comes as standard, and go. Just a few seconds have passed.About those lenses too. Oakley High Definition Optics don't bend light before it enters the eye. So distortion is stopped and the view is sharper.And the Three-Point Fit provides comfort by making sure Split Jacket only touches your head in three places. Unobtainium nose pads and earstem sleeves grip more with perspiration. Split Jacket won’t slip.