The Gl-121 AmeriGlo Classic tritium Night Sight green front and yellow rear dots with white outline fit Glock Models G20 21 29 30 31 32 33 36 CNC machined sight sets feature a three-dot aiming system with glowing dots for low light shooting. AmeriGlo sights are machined from US-made bar stock steels and assembled using Swiss-made tritium light sources. AmeriGlo sights are used worldwide by law enforcement, military, defense minded free citizens, and recreational shooters. The "Classic" AmeriGlo models feature a white outline surrounding the tritium dots for increased visibility. The AmeriGlo "Operator" models have no outline around the rear dots, so attention is focused more on the front sight for tactical, point shooting.