Costa Ludus sights include a proprietary Night Fision Perfect DotA(R) in the front sight and a horizontal tritium bar in the rear sight for a unique and unmistakable sight picture. Serrated for low-glare their shorter height stays well out of the way of your dot for a minimal co-witness. 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 Glock 17 17L 19 22 23 24 25 26 27 28 31 32 33 34 35 37 38 39 (Including MOS Models)