The M Frame Sweep is where Oakley really separated themselves from the sport sunglass masses. Deliciously curvy and classic, it was both organic and otherworldly. It turned the sports shield market on its head and everyone else had to race to catch up. Even though there are newer designs, the classic M Frame is still around and going strong, here with Iridium lenses.The M Frame does a number of things really well. Their radically-curved single lens packages super protection in a minimal shape, offering incredible clarity. The three-point fit is both comfortable and firm. The arms stay out of the way of helmet straps without being obtrusive. The Sweep lens is a classic shape that works best on small to medium sized faces. The frame and hinged temple pieces are the usual light, sturdy, flexible O-Matter. The nosepieces and ear socks are Unobtanium rubber. This stuff gets stickier the more you sweat. And if it ever wears out, the Unobtanium pieces can be replaced.The Oakley M Frame Sweep Iridium is available in two versions -- Crystal Red w/Positive Red Iridium lens and Polished White w/Jade Iridium lens. Positive Red is a high-contrast base with a mirror coating for sunny days; it allows 15% light transmission. Jade has a neutral green base with a mirror coating for sunny days; it allows 17% light transmission. You'll get a soft bag that doubles as a cleaning cloth. All M Frame lenses will fit in an M Frame.