The DISTRICT's new interchangeable lens system creates a sleek and subtle design allowing comfortable wear in the city or on the trails. Smith's Interchangeable lens system utilizes distortion-free, 9 base lenses to provide precise optical clarity and maximize coverage while minimizing peripheral exposure to sun, wind, and glare. With over a dozen replacement lens tints to choose from, the Smith Slider series provides versatility across the full spectrum of light conditions and sport eyewear enhancements. FEATURES Medium Fit Non Polarized include 3 sets of lenses Polarized include 4 sets of lenses 9 base TLT™ Carbonic™ Lenses Grilamid™ TR90 Nylon Frame Hydrophilic Megol™ nose/temple pads 100% UVA/B/C Protection Distortion-Free Polarized Lens Model - smithsport.com