The PRI Mark 12 Mod H Upper Receiver Assembly is a ready to shoot 5.56 upper with MOA accuracy. The Mark 12 Mod H Upper is equipped with a 16? Douglas 416 stainless steel barrel with a fitted bolt, and commercial bolt carrier. The Mark 12 Mod H has a flat-top picatinny receiver, PRI rail mounted flip up front and rear sights, pri upper mk12 and rif