Night Fision's patented injection molded sleeve design holds the tritium vials securely in place using ballistic materials. Night Fision night sights carry more tritium than the average night sight on the market and a domed lens engineered to create the a crisp defined glow.Features:a Brightest Tritium Night Sights on the marketa Domed lens collimates tritium rays for a sharper sight picturea CNC Machined out of high quality steela Black Nitride coating used to improve wear and corrosion resistancea Installation: Gunsmith Recommendeda Built in the USA with Swiss Tritiuma Fits Sig Sauer P-Series pistols with #6 Front and #8 Rear Sights