The FACTOR D-Max's Polarized interchangeable lens system creates a sleek and subtle design allowing unobstructed peripheral view perfect for the running trail, golf course, or weekend ride. 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. The Factor D-Max features an extra large lens for increased coverage on larger faces.