Myself I needed custom glasses, being far sighted it had been years since I had seen a clear front sight post. Had my rifle glasses focused to my M1A. The diopter is n the upper right corner of the right lens, that way when I am down on the stock it's in the right place. My pistol glasses have a diopter thar runs all the way across the center of the lens and is focused on the front sight post of my CZ P09. Both the left lens are clear. And as stated above they are coated with antifog. When I got my first set we weren't carrrering eye insurance so the exam and both pair ran about $850. We have it now and every other year I can get a new pair. Another thing is finding a optometrist that will do it. Family Eye Care in Lewiston was where I got mine Dr Gov is great, she is a shooter and hunter.