Tritium phosphor-filled glass lamp provides battery-free glow, allowing for a visible sight picture in all lighting. Each Trijicon tritium lamp is capped with a sapphire jewel that helps evenly distribute the light from the lamp and also acts as an additional layer of protection from puncture and cleaning solvents. White-painted rings around tritium lamps enhance user's ability to see sight picture in bright-light shooting situations. Tritium gas lamps are contained within protective aluminum cylinders and have additional silicone rubber cushioning. Trijicon RMR Mount w/Integrated Bright & Tough Black Outline Front/Rear Night Sight Set for Sig Sauer M17/M18 Commercial Variant 601124 — instant low-light sight picture, increased daylight dot visibility, and enhanced protection from recoil and solvents. Package includes mounted sight assembly sized for SIG Sauer M17/M18 commercial variant.