The Trijicon Bright & Tough SRO/RMR HD Mount/Integrated Night Sight Set for FN 601158 is a versatile accessory designed for FN 509 handguns. This mount integrates the Bright & Tough night sights, providing a clear and precise aiming point in low-light conditions. The durable construction ensures long-lasting performance, while the no tritium design offers a reliable sight picture without the need for illumination. This mount is perfect for shooters seeking enhanced accuracy and versatility.