Z33G-Tech are both light and aerodynamic and the G-Tech lens gives added Contrast and Minimal Glare You’ll spot them right away. They’re the lenses with the high-tech rainbow appearance. G-Tech Multi-Layer Lens Technology by Global Vision, gives you the benefits of discoveries made by aerospace engineers at NASA. You’ll enjoy enhanced contrast and minimal glare, which is especially helpful around water. These high-tech lenses have from 7 to 13 layers of titanium dioxide and silica applied onto shatterproof polycarbonate. Cleaning them is easy and they are scratch resistant. Another benefit: they look cool on everyone. And like all Global Vision products, you get 100% ultraviolet protection.