Street smarts on the bike means rider tuned vision. The S21X was designed to look and perform well for riding and casual wear off the bike. The frame is built from a lightweight, strong, and durable Grillamid TR90 material so you don't have to worry about crushing them. The lenses are strong, rigid, and lightweight and offer a full UV400 protection to comfortably shield your eyes even when the sun shines brightest. Anti-fog and anti-scratch treatment round out the package.