Angstadt Arms complete upper receiver assembly is ready to run out of the box with a sound suppressor! This pistol upper features a 9mm 3-lug muzzle brake, Blastwave blast shield and Radian Weapons Ambidextrous charging handle. Compatible with any 9mm GLOCK(R) and COLT(R) style AR-15 lower receiver. Features: 7075-T6 billet aluminum slick side pistol caliber upper receiver with appropriately sized ejection port 4.5? 9mm lightweight profile barrel made from 4150 chrome-moly steel with a 1-10" twist rate. 1/2x28 TPI 4" ultra light hand guard with M-LOK(R) mounting interface on the 3, 6, & 9 O'clock positions The hand guard features 2 QD swivel mounting points and a continuous top mil-spec 1913 picatinny rail with lightening cut Handguard ID: 1.375* The last 3/4" of the handguard is bored out to 1.405", allowing most aftermarket sound suppressors 1.39" in diameter and smaller to tuck inside of the handguard Black nitride 9mm AR-15 bolt carrier group. For use with a standard AR-15 hammer Compatible with both GLOCK(R) and COLT(R) style 9mm dedicated lower receivers. Angstadt Arms 3-Lug muzzle brake Angstadt Arms Blastwave blast shield Radian Weapons ambidextrous LT charging handle Weight: 2.6 lbs Caliber: 9mm NATO