Trijicon bright & tough Suppressor night sights are three-dot tritium iron sights that allow shooters the ability to line up their sights in both bright and low-light situations. While standard height sights do not provide an aiming solution when using a suppressed firearm; the additional height of Suppressor night sights will clear the added height of a Suppressor, allowing shooters the ability to line up their sights on target. Additionally, Suppressor night sights can be used as back up iron sights with the Trijicon RMR. Specifications: - fits: FNH models FN509 (white front/white rear with green lamps). note: professional installation recommended.