Trijicon designed this HD XR Front Sight for Sig Sauer .40 & .45 as the next level of advanced target identification and engagement at increased distances. This thinner sight post allows shooters to have a larger field of view that enhances their ability to identify targets, expedite engagements, and see hits at longer distances. The device features a green battery-free tritium phosphor lamp surrounded by a photoluminescent yellow outline disk. For durability, the lamp is encapsulated in an aluminum cylinder with a silicone rubber cushion and covered with a sapphire window. The window acts as a beam-shaping lens and protects the lamp from solvents that are commonly used to clean firearms.