Native Gonzo Polarized Sunglasses Double Snap-Back Interchangeable Lens System Rhyno-Tuff Air Frames Venting System: Exhaust vents are incorporated into the design framework to enhance airflow, and virtually eliminate fog and condensation, while strategically placed hybrid vents and side vents (available on select models) keep frames snugger on your face without compromising fit. This unique design feature is the only system available that allows maximum ventilation while blocking extraneous incoming light. Cushinol: Cushinol nose pads ensure a soft feel and custom fit, regardless of nose shape or size, and Cushinol temple boots create a non-slip grip to keep sunglasses in place during athletic activity Cam-Action Hinges: This patented feature allows the temple to quickly lock into position