Day or night, TRUGLO X sights are always ready. With an ultra-durable sealed capsule design, solid steel body and a 12-year mfg warranty, TFX sight are built to last and to perform when brightness counts. Built with a sealed capsule and Fortress finish to handle just about anything. F.A.S.T Rear Sight: A simplified combination of a battue-style sight and express sight provides quick and intuitive sight picture. TFX Front Sight: The combination of a Tritium vial, fiber-optic, and FOCUS LOCK ring provides a bright and accurate point of aim in any light. Tritium vial glows constantly - Fiber-optic gathers and directs surround ambient light Optional Purchase: Change rear sight insert colors for increased visibiltiy and a custom look : Green - Orange - White - Glow-in-the-Dark (White is included with this purchase).