When you need to make a fast and accurate shot, brightness counts. TruGlo brought fiber-optics to the shooting sports industry years ago for this very reason. They have now paired them with their tritium night sights to create a consistently bright sight picture-day or night! Their patented combination of Tritium and Fiber-optic technologies unites the best of both worlds. Whether you are in glaring daylight or complete darkness, you can count on TFO(R) to provide a bright and reliable sight picture. These night sights are for Smith & Wesson models M&P (excluding Shield and 22 models, .22 compact and C.O.R.E models), and SD9/SD40 (excluding VE models). Uses the patented TFO technology The ultimate handgun sight Unbelievable transition through all light conditions Glows in the dark No batteries required CNC-machined steel construction Concealed fiber cannot be seen by target Fits standard holsters Snag-resistant design