AmeriGlo AmeriGlo GL-615 Cap Grn Set For Glk 20/21 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"