Their specialization is in "self-luminous" [[optics (firearms)|optics]] and [[night sights]]. These use the slightly [[radioactivity|radioactive]] [[isotope]] [[tritium]] combined with light-gathering fiber optics, and in certain products a [[battery]]. | Their specialization is in "self-luminous" [[optics (firearms)|optics]] and [[night sights]]. These use the slightly [[radioactivity|radioactive]] [[isotope]] [[tritium]] combined with light-gathering fiber optics, and in certain products a [[battery]]. |