Quality could have been better - FAB Defense Top Mounted Deployable Front and Rear Set of Flip-up Sights

The material is sturdy, they stay in place on the rail well, the FDE color is spot on. What is the problem? The rear sight aperature. There are two apperatures sizes to flip between but the "large" is actually tiny and I don't believe that is the design intention. The large apperature has an irregular inner edge, it looks as though the body wasn't cast quite right, as if too much of the polymer material was poured into the mold and the excess pooled into the bottom of the bowl of the large aperature and nobody went back to clean up the mess. If they hadn't been a "final sale" item I would have returned them. If I can't open the larger rear aperature enough with a fine point file to be usable they'll be tossed as a total loss. I was trying to save a little money after having bought the metal Magpul MBUS Pros for my other gun, I have other FAB Defense accessories that I have been pleased with, but these were a total disappointment. I wish now that I had at least gone for the polymer Magpul MBUS sights instead.