GI style is Narrow Tenon Post from the factory. Rear has a standard Novak cut. Fusion removes factory Sights prior to coating and installs new Sights after coating at a cost of $24. Had purchased the Sights from Fusion 2 - 3 years ago for another RIA and never used them. Like the Sight Picture better with the White Outline.Very nice.....how much fitting did the sights require?