The Holosun SCS VP9 reticle is a game changer for the VP9 series of pistols IMO. I bought the green reticle version and I’m very impressed by the advancement and ergos that this dot achieves. It mounts without a plate. The base is about the thickness of two, maybe 2.5 H&K VP9 optics plates. The sight has two lugs that fit into the intentions in the slide for an optics plate. So, in addition to the screws, you have the two lugs and the tight fit into the milling on the top of the slide to stop shearing forces during recoil. You can keep your stock irons because they co-witness with this dot. The dot charges itself and has a built-in battery. Jury is still out on that feature, but so far I have had no problems with my sample of one. Reticle is crisp, I turned the circle of death off and went dot only. If you have an astigmatism, get a green dot instead of red: there’s less “flare” with green and it’s easier on your eyes. If you have I VP9, I recommend that you examine this sight for sure. Holosun makes a closed emitter version too.