M9109 ASW/AC MLA

The 50mm point defense gun is a United Nations Space Command starship-mounted weapon.

These weapons are are used aboard warships for "point-defense", interception of nearby enemy starfighters, while the primary armament of UNSC vessels, typically nuclear weapons or Magnetic Accelerator Cannons, are used to engage hostile capital warships.

50mm point defense guns are standard armament for UNSC Halycon-class Cruisers and are usually controlled by the ship's Artificial Intelligence.

On Alpha Halo, the ODSTs that recaptured the Pillar of Autumn from the Covenant scavenged 50mm point defense guns from the crashed Halycon-class cruiser and mounted them on Pelicans for transport to Alpha Base.