The Meprolight 404100, also known as the Fubs, features tritium-enhanced, self-illuminating front and rear back-up sights. These secondary sights are designed to aid shooters if the primary optics were to fail. Being advanced and robust, Fubs sights combine low-profile designs with the benefit of tritium-enhancement.The functionality of Fubs sights goes beyond the usual. These auxiliary sights can be quickly folded up or down to cater to the shooter\'s specific needs. Adjusting the sight pin elevation is a hassle-free process that requires no tools. Furthermore, the Fubs sights can be easily mounted on any 1913 Picatinny rail, ensuring wide range compatibility.