The Meprolight 403440, also known as Fubs, are state-of-the-art back-up sights enhanced with tritium for self-illumination. Designed to serve as secondary sights should the primary optics fail, they offer reliable support to the shooter.These front and rear back-up sights stand out with their advanced technology and low-profile design. They are not only durable but also greatly beneficial due to their tritium-enhanced illumination. The versatility of Fubs allows them to quickly fold up or down to align with the shooter\'s needs.One exceptional feature of the Fubs sights is the tool-free adjustment of sight pin elevation. This handy trait ensures quick and easy alterations. Installation is also a breeze as they can be readily mounted on any 1913 Picatinny rail.