When your customers say ( I want a 1000 Yard gun with 0 drop ) THIS IS IT! Built with our AAT upper and lower designed for easy takedown and maintenance with us replacing roll pins with set screws to make it easier for you to replace parts when needed, our slick LPK with a nice smooth finish (not gritty like others in the industry) which allows a easy and smooth trigger pull , our Black nitride 224 BCG allowing a smooth glide with no hangups, AAT Mil-Spec buffer tube with a TF buttstock for comfort during competitive shooting. Also included is a IMI pistol grip, our ultra light trigger guard and our Mil-Spec charging handle. This model comes with our 18" 4150 steel 1/7 twist barrel along with our solitary clamp on gas block/yes we eliminated the set screws which always break loose and cause feed problems and in conection with our upgraded gas block comes a black nitride Mid Length gas tube with our anti corrosion stainless steel roll pin connecting the two together. We've installed our 14" alignment free handguard/yes NO lining up the handguard with the barrel nut to get it set straight, this design pops right on and tightens down even a child could install and at the end you'll find our pineapple brake which functions flawlessly. Yes everything on a Alien build is Mil-Spec.