I second what WingedMelon said. I have many Holosun optics, together with this a person, and have never had a problem with any of them. I am really selling my Trijicon RMR to obtain A further a person. The 507 is on par, Otherwise superior, than my DPP.Produced my first purchase from D4 a pair months in the past, an old Colt revolver in .32-twenty.