Lightly used ArmaLite U15A4BX AR15 medium profile upper, complete with a charging handle, bolt carrier group and folding front sight. This Armalite U15A4BX upper features a 20″ free-floating medium competition barrel with a 1:8 twist rate easily capable of sub-MOA groups. The free floating handguard includes front & rear picatinny rails, with several attachment points and mounting options.