I have done a search and cant find the answer I'm looking for. Maybe you guys can help. I'm gonna buy a set of night sites and my LE dealer will put them on for free. I have been looking and will probably get trijicon or mepralites. However, I see 6.5 or 6.9 when looking at the sites. what is the difference? What is the closest thing to stock size? These are going on a G23 and I might get a set for my G27. Thanks for the help.