Rectangular shape non polarized UV400 gray lens flip-up that clips onto rectangle shape prescription glasses. The lenses are polycarbonate and scratch resistant. Flip-ups work best for glasses that closely resemble the shape of the flip-up. It also fits best if the frame is straight across the top so that when the flip-up clamps onto your glasses it is sitting straight across the top of your glasses. Measure your glasses width x height. It is best to add 2mm's to the height of the flip up height to accommodate for how the flip up clamps onto your glasses. It is usually okay for the flip up lens to be a little wider or higher than your glasses, it will just overlap a little.