GLOCK night sights are equipped with contrasting tritium inserts, enabling simple, accurate and quick target alignment in all light conditions. Night-sight Position: Front (Fits all models) Position: Rear Size: 6.9mm. Fits all models EXCEPT G42 and G43. Standard height on G20, G20SF, G21, G21SF, G29, G29SF, G30, G30SF, G30s, G31, G32 (Including Gen4), G36, G36