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! Truglo 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 to provide a bright and reliable sight picture. Fits S&W M&P (including SHIELD & .22 models, excluding .22 Compact / C.O.R.E. models), SD9 and SD40 (excluding VE models) Uses Truglo's 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