TRUGLO Brite-Site TFX Pro, Sight, Fits Glock 42 and 43, Tritium/Fiber-Optic, Day/Night Sight, 24/7 Brightness, Orange Ring on Front Sight TG-TG13GL3PC They created the original TFO(R) day / night sight" then made it virtually indestructible with their hermetically-sealed TFX(TM) sights. Now" they are taking TFX(TM) technology to the next level for professionals and shooters who demand maximum performance from their handguns-providing ultimate reliability" accuracy" and brightness no matter how tough things get.