TRUGLO TFX Pro, Sight, Fits 3 Officer and 4.25 Commander 1911 with Novak Cut , Tritium/Fiber-Optic, Day/Night Sight, Orange FS Ring TG-TG13NV3PC 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.