Trigger shoe is machined form a billet of 6061 aluminum on state of the art CNC machinery. No need to remove the trigger from the gun to addjust the trigger. Pre travel and over travel can be adjusted witht the trigger in the gun. An oversized safety spring and a safety lever that is flush to the shoe make it more comfortable to the shooters finger. The 9/40 versions are intended for the Glock® Gen 3&4, gunsmithing may be required on Gen 1&2.