The better you can see your sights, the better you can shoot. We brought fiber-optics to the shooting sports industry decades ago for this very reason. TFO pairs our fiber-optic sights with our tritium night sights to create a consistently bright sight picture day or night! Our patented combination of tritium and fiber-optic technologies unites the best of both worlds providing the same bright sight picture whether you are in glaring daylight or complete darkness. Fits Glock 42, 43/43X, & 48 (excludes M.O.S. models).