Tapco TAP22040: Tapco Tritium Sights offer brighter, more vivid, aiming dots. These night sights with the use of Tritium are always on, making them more effective. The Tritium insert is surrounded by a daylight-fluorescing material that produces optimum visibility in daylight. Tapco sights provide maximum visibility in both nighttime and daylight conditions, you\'ll be able to locate your sight faster and get them on your target.