Great question! Your prescription lenses fit behind the electrochromic lenses. -- The prescription lenses go in an inner groove, whereas the electrochromic one

Great question! Your prescription lenses fit behind the electrochromic lenses. -- The prescription lenses go in an inner groove, whereas the electrochromic ones are mounted flush to the front face. You can get dirt-cheap lenses at http://zennioptical.com http://zennioptical.com , and you or any optometrist can insert them.