The Meprolight ML 11517 is a set including Tru-Dot rear and front sights for Heckler and Koch USP Compact pistol. These combat proven self-illuminated night sights enable you to hit stationary or moving targets under low-light conditions with dramatically increased hit probability. Meprolight sights, like other self-illuminated products and devices from the same brand 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 12 years of usable light under all weather conditions.