Meprolight ML 10110 Tru-Dot Fixed Night Sight Set for Sig Sauer P frames, 9mm/0.357 (Yellow/Green)The Meprolight ML 11517 is a set including Tru Dot rear and front fixed sights for Sig Sauer P Series 9mm and . 357 pistols. These combat proven self illuminated night sights enable you to hit stationary or moving targets under low light conditions with dramatically increased hit probability. They use a phosphorescent gas called tritium to illuminate three sight markers for day and night visibility. The tritium gas eliminates the need for batteries