This is a AmeriGlo Sight known as the CAP - Combative Application Pi, model GL-615.
AmeriGlo CAP (Combat Application Pistol) sets allow the shooter to align a highly visible front post with a brightly colored horizontal paint bar on the rear sight for rapid target acquisition. Point of impact is the A-Box at 15 yards when any portion of the front sight is visible in the rear notch" allowing for rapid sight alignment.
Features:
Green tritium .140 wide square LumiGreen outline front;Flat black .155 wide square notch with horizontal LumiGreen paint stripe under notch rear
