I 2nd what WingedMelon said. I have numerous Holosun optics, like this one, and have not had a problem with any of these. I am basically selling my Trijicon RMR to have One more one particular. The 507 is on par, if not superior, than my DPP.Its name for trustworthiness and longevity has designed it a favorite preference amid armed forces snipers w