davp11511wrote a review of Oakley M Frame Sweep Sunglasses on July 2, 2013
Familiarity: I've put it through the wringer
Lenses sometimes fall straight down and out of the frame when I am riding.
This happens when the frame is held in place by my helmet straps.
Oakley must have had a quality control problem at some point. You would be better off getting a product where lenses snap in tighter to frames.