This is a Trijicon Sight known as the Tritium, model WP01-600505.
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.
Features:
Instantly Visible Sight Picture In No-Light Or Low-Light Situations
Increased Daylight Dot Visibility
Enhanced Protection From Heavy Recoil And Harsh Cleaning Solvents
Evenly Distributed Light
