I have owned this style of Gargoyles for over ten years. I must have 8 pair, never lost any of them but they do get scratches that can be a problem. Never lay them on the dash board where they could get turned over to the lens side and rock and roll in the dust. The coating on the lens is good but it can get scuffed or scratched. PUT THEM IN THEIR CASE.... I do a lot of 4 wheeling and when they get dusty and dirty, rinse them in warm water.
  I got my first pair from the eye doctor. He sold them at his office. A great accesory to the glasses was a small pair of perscription glasses that are held in by the nose piece and allow me to drive my car with perfect vision. The wrap around style is great for cutting down side glare, and wind in your eyes if you drive a convertible or Jeep type vehicle.
  The grey flash silver, or mirror , are my favorite, but I also have dark blue and black.