Trijicon Tritium Night Sight, Fits FN 509, 3 Dot FN04-C-600988 There's a reason so many Trijicon(R) night sights are trusted by local" state and federal law enforcement agencies" as well as the most discerning pistol sports shooters on the planet: they're designed for faster target acquisition in any lighting situation" as well as designed to take on abuse and still operate with precision. Upgrade your iron sights with proven" superior aiming solution technology.