20mm Dummy Round CIWS *Demilitarized* **PAPERWEIGHT** 20mm MK149 Round OEM **INERT Fired by the Phalanx Weapons Sytem CIWS. 20mm M61 Vulcan Gatling Gun. The Phalanx CIWS (SEE-wiz) is an automated gun-based close-in weapon system to defend military watercraft automatically against incoming threats such as aircraft, missiles, and small boats. , Pomona Division,[3] later a part of Raytheon. Consisting of a radar-guided 20 mm (0.8 in) Vulcan cannon mounted on a swiveling base, the Phalanx has been used by the United States Navy and the naval forces of 15 other countries. The U.S. Navy deploys it on every class of surface combat ship, except the Zumwalt-class destroyer and San Antonio-class amphibious transport dock.[5] Other users include the British Royal Navy, the Royal Australian Navy, the Royal New Zealand Navy, the Royal Canadian Navy, and the U.S. Coast Guard. A land variant, the LPWS (Land Phalanx Weapon System), part of the Counter Rocket, Artillery, and Mortar (C-RAM) system, was developed.[6] It was deployed to counter rocket, artillery and mortar attacks during the 2021 US withdrawal from Afghanistan.[7][8] The U.S. Navy also fields the SeaRAM system, which pairs the RIM-116 Rolling Airframe Missile with sensors based on the Phalanx. The M61 Vulcan is a hydraulically, electrically, or pneumatically driven, six-barrel, air-cooled, electrically fired Gatling-style rotary cannon which fires 20 mm × 102 mm (0.787 in × 4.016 in) rounds at an extremely high rate (typically 6,000 rounds per minute). The M61 and its derivatives have been the principal cannon armament of United States military fixed-wing aircraft for over sixty years.[2]