This is a Truglo Sight known as the Tritium Pro, model TG231G2W.
Simply put" TRUGLO(R) manufactures bright ideas. When TFX(TM) PRO sights immediately took off and gained critical acclaim" they noticed that the world of TRITIUM night sights needed a similar upgrade. Starting with the brightness and durability of their original TRITIUM night sights" they added all of their PRO level features to give you the advantage when you need it the most.
Features:
Front sight FOCUS/LOCK ring for even faster focus
Quick and accurate U-notch Design
Angled rear sight edge for emergency one-hand operation
Swiss Tritium for maximum brightness
Glows-in-the-dark
FORTRESS FINISH provides a permanent protective coating for maximum protection
Snag resistant design / fits standard holsters