New GSE A3M4 combat Tactical carbine with intergraded rail system w/ front and rear flip up sites as shown. Upper and lowers are mfg. on the same CNC machine. Receivers will interchange with most all other AR receivers. This comes standard with a 2 stage match trigger on both Ras 1 and Ras 2 models. Forward Pistol Grip Included. Optional on other models.