Tritium-filled glass lamp provides superior illumination in no light or low light conditions; 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; All Bright & Tough Night Sights feature a white ring around the glowing dots for daylight visibility; Contains and protects the tritium gas filled lamps from heavy recoil and harsh cleaning solvents; Each sight is manufactured to fit specific handgun makes and models; Gives additional shock protection to tritium filled glass lamps within the aluminum housing; Tritium lamp is warrantied to illuminate for 5 years on orange lamps, 12 years on green and yellow lamps from date of original manufacture