Angstadt Arms complete 16" upper receiver 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 rifle, this completed upper receiver is compatible with both GLOCK(R) and COLT(R) style 9mm magazines. This item will not ship to the following states: CA, NY, HI, NJ, CT, IL Features: 7075-T6 billet aluminum slick side pistol caliber upper receiver with appropriately sized ejection port 16? 9mm barrel made from 4150 chrome-moly steel with a 1-10" twist rate. 1/2x36 TPI 15" ultralight handguard with M-LOK(R) mounting interface on the 3, 6, 9 & 12 O'clock positions Top mil-spec 1913 picatinny rail with lightening cut 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 9mm flash hider Mil-spec charging handle Caliber: 9mm NATO