This Meprolight Tru-Dot Night Sights set is a great accessory for shooters who don?t want to pack their rifles up when the sun goes down. These self-illuminating sights replace the stock iron sites on Sig Sauer P-series 9mm and .357 pistols with #8 front and rear sights. They use a phosphorescent gas called tritium to illuminate 3 sight markers for day and night visibility. The tritium gas eliminates the need for batteries and the sights are guaranteed by Meprolight to provide usable illumination for 12 years. These sights are custom designed for Sig Sauer 9mm and .357 pistols to ensure a perfect fit and feature green illumination. Features Specifically Designed for Sig Sauer P-Series 9mm and .357 Pistols with #8 Front and Rear Sights Replaces Stock Iron Sights Battery-Free Tritium Gas Illumination Made of Anodized Aluminum 12-Year Usable Illumination Manufacturer Warranty.