In sport, your focus must stay on the field of play. There's no time to spare worrying about your glasses. That's why select Nike sun and ophthalmic frames incorporate Flexon, a highly flexible and durable patented metal alloy that moves with you. Unlike conventional metal frames, Flexon frames are nearly impossible to bend or twist out of shape because their "memory metal" content allows them to return to their original form every time. Flexon is 25% lighter than standard metals, so frames are more comfortable. Highly resistant to metal fatigue, Flexon frames easily withstand the rigors of sport without kinking or breaking. With the same corrosion-resistant quantities as pure titanium, colors and finishes retain their original look longer.