Angstadt Arms complete 5.56 NATO AR-15 16" upper receiver assembly is ready to run out of the box with any AR-15 Mil-Spec lower receiver. It features the same high quality parts that go into are UDP-556 rifles. This item will not ship to the following states: CA, NY, HI, NJ, CT, IL, MA, DE, WA Features: 7075-T6 billet aluminum slick side upper receiver with no forward assist or dust cover 16" M4 profile barrel in chrome moly with a 1/7 twist rate, black melonite finish and a 1/2x28 thread pitch M4 feed ramp extensions Mil-spec 5.56 complete bolt carrier group assembly finished in black nitride 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 Angstadt Arms black nitride A2 birdcage flash hider .750? low profile gas block with carbine length gas tube Mil-spec charging handle Caliber: 5.56 NATO Color: Available in a Black anodize finish, Magpul FDE (Flat Dark Earth) or Tactical Grey Cerakote