This M-4 barreled upper comes standard with a 4140 chrome-moly steel barrel. The 16” M-4 barrel is mounted on aircraft quality aluminum upper. Barrels are plated evenly with tough parkerized finish. Comes fully assembled (minus bolt/carrier and charging handle optional upgrade) with forward assist, ejection port cover assembly, gas tube assembly and heat shielded, oval shaped m-4 hand guards. Comes with M-4 Feed Ramps.