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. BIS, G43X/48 consists of the following: Front sight, available with either green Tritium and white outline (no serrations), or serrated front sight, no tritium or white outline. Rear sight, serrated. BIS, G43X/48 is slightly different from GL-527 on which it's based. These FCD particular c Mfg: Forward Controls Design