Most good quality dot scopes will work for this. You can choose between tube types of various sizes (some are humongous), heads up display types, Holo Sights, Eotechs, etc. Ya got to decide what you want to do with it. Short range quick aquisition needs a bigger dot and a bigger tube. Longer range or target work needs a smaller dot. Some folks, myself included, feel that dots are better than iron sights for us with tired eyes. You can spend as little as $60-$80 or as high as $300+. You can even get some cheaper, but they're not very good.