Base Curve: 8. Grilamid: Grilamid is a resilient type of nylon specifically formulated for flexibility, stability, and durability. A tested and proven workhorse ready to get into the mix. Comes with the SPY Happy Lens™, the only color and contrast enhancing lens technology that maximizes the transmission of the sun's "good" rays—while still blocking out its "bad" rays—which studies suggest fosters an uplift in mood and alertness.