Complete 9mm upper receiver pistol assembly with 4.5″ barrel and 4″ hand guard. Ready to run with any 9mm AR-15 dedicated lower receiver.Includeds 9mm BCG and Charging handle. Angstadt Arms complete upper receiver pistol assembly is ready to run out of the box with any 9mm AR-15 lower receiver. Featuring the same high quality parts that go into are UDP-9 pistol, this completed upper receiver is compatible with both GLOCK® and COLT® style 9mm magazines. Features: 7075-T6 billet aluminum slick side pistol caliber upper receiver with appropriately sized ejection port 4.5″ 9mm lightweight profile barrel made from 4140 chrome-moly steel with a 1-10” twist rate. 1/2×36 TPI 4” free float hand guard with a modern, ergonomic, 7 side design The hand guard features 2 QD swivel mounting points, M-LOK® mounting interface on 7 sides and a continuous top mil-spec 1913 picatinny rail Handguard ID: 1.375* The last ¾” 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® and COLT® style 9mm dedicated lower receivers. A2 style flash hider Mil-spec charging handle Weight: 2.5 lbs Caliber: 9mm NATO