Primary arms are gtg, they can take a beating. The problem with red dots is if you have astigmatism in your right eye they will look funny, grapes, squiggly for example. Reflex or holosights dont suffer the same problems. I had a pretty bad astigmatism before lasik. Most red dots the dot looked fuzzy not a sharp round dot. I had a bushnell holosight and it looked perfect. Although true reflex holographic sights are usually more expensive. Eotech, trijicon makes a few. Used first or secong gen Bushnell holosights can be found for good prices these days and are actually pretty good sights.