The ML11766 is a fixed set for the Smith and Wesson M&P full size and compact 9mm and .40 caliber pistols. Please note, S&W offers many heights of front sight. Meprolight produces the most common height. MEPROLIGHT sights, like our other self-illuminated products & devices take maximum advantage of tritium light sources - the fail-safe, maintenance-free light sources that don’t require any external source of energy and provides up to 15 years of usable light under all weather conditions. MEPROLIGHT continues to offer the strongest guarantee in the industry for the usable light of our TRU-DOT sights.