This 20" A4 Gov't. Profile Upper Assembly is designed for the shooter who plans to add a scope or optic, or already owns an A4 Carry Handle. It is a complete Upper Receiver Assembly - ready to snap onto your Lower. The barrel is chrome lined and machined from 4150 Chrome Moly Vanadium 11595E steel, rifled 1 x 7" RHT. An standard A2Front Sight base with sling swivel fitted. The assembly includes premium quality rifle length handguards molded from a fiberglass composite for heat resistance in sustained fire - they will not deform when subjected to high barrel heat.