Trijicon HD XR Night Sight Set, 3 Dot Green Tritium With Yellow Front Outline, Fits Glock 17/19/26/27/33/34 GL601-C-600835 TRIJICON HD XR NS FOR GLK 9/40 YELL: Building on the features of the current HD(TM) Night Sights" the Trijicon HD XR(TM) night sights are for the next level of advanced target identification and engagement at increased distances. A thinner front sight post allows shooters to have a larger field of view which further enhances the ability to identify targets" expedite engagements and see location of hits on target at longer distances.