Trijicon 3 Dot Front And Rear Night Sight Set for Colt Officers WHITE RINGS: Bright & Tough Night Sights feature a white ring around the glowing dots for daylight visibility TRITIUM-PHOSPHOR LAMP: Tritium-filled glass lamp provides superior illumination in no light or low light settings SAPPHIRE WINDOW: Each Trijicon tritium lamp is capped with a sapphire jewel which helps to evenly distribute the light from the tritium lamp as well as protect it from solvents and puncture PROTECTIVE ALUMINUM CYLINDERS: Contains and protects the tritium gas filled lamps from heavy recoil and harsh cleaning solvents FITS: Colt Officers, Officers ACP, Compact 1991A1 (.45); and Para Ordnance P12 with stake-in front (excluding the Limited version)