Increased Height: Specially engineered to allow use with a suppressor or as backup iron sights for a slide-mounted red dot sight, such as the Trijicon RMR Instantly Visible Sight Picture in No-Light and Low-Light Situations: Tritium phosphor-filled glass lamp provides battery-free glow, allowing for a visible sight picture in all lighting situation Enhanced Protection from Heavy Recoil and Harsh Cleaning Solvents: Tritium gas lamps are contained within protective aluminum cylinders and have additional silicone rubber cushioning 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 Fits Glock Models: 17, 17L, 19, 22, 23, 24, 25, 26, 27, 28, 31, 32, 33, 34, 35, 37, 38, and 39