Battle Arms Development WORKHORSE, Upper Receiver Assembly, 223 Remington/5.56 NATO, 10.5" Barrel, Carbine-length Gas System, Anodized Finish, Black, A2 Flash Hider, WORKHORSE 9.5" M-LOK Free Float Handguard, Does Not Include Bolt Carrier Group or Charging Handle WH-UR-10.5-556