This gas block replaces your existing front sight to provide a simple low profile design that can be used to mount a rifle length forearm to a carbine length barrel. It is mounted by the use of two set screws (YHM-9383) and is .950 Inches long. Manufactured from high quality steel and finished with a mil. spec. phosphate coating. This gas block has a bore diameter of .750 inches.. Made in the U.S.A. Manufactured from 4140 Steel, finished with a mil. spec. phosphate coating.and finished with a mil. spec. phosphate coating.Length: 0.95"Bore diameter of .750 inches.Weight:1.6 Oz.