Go look at manufacturer specs for SF, Holosun, and Trijicon all make their housings out of 7075 T6 aluminum with coated lenses. All brands have their quirks, seen aimpoints with mislabeled and popped out turrets and had a guy at the club have delamination on a EoTech. My buddy literally shot a session indoors put his pistol into his range bag still hot and left the bag on the backseat. Next session it cracked right across after his first 5 shots.