BIS, G43X/48 (Backup Iron Sight, G43X/G48) is a collaboration between Ameriglo and FCD. Specifically made for Glock G43X and G48, these sights are based on the superb Ameriglo GL-527 with a front sight height of 0.450", and a rear sight height of 0.554", this sight sets provide lower 1/3 co-witness with the Trijicon RMRcc when used with our OPF-G43X/43, RMRcc on G43X and G48.