This is a Wilson exclusive that was a limited run.12.5 inch upper so this is an SBR if mounted on a regular lower. Pistol brace or SBR lower only. Upper is 5.56 Heavy barrel Chrome moly for ful auto fire, AAC muzzle brake for quick connect AAC suppressor. Knight armament furniture and SOF issued rear pop up sight. Used but not abused around 400-600 rounds through the barrel. Asking $650